ESP MITSUBISHI DIAMANTE 1900 Owner's Manual

.
3-68 ENGINEANDENGINEOVERHAUL
crankshaft end-play 8. Install the rear main seal.
the inner portion of the lower land. If the lower
9. After the bearings have been fitted, apply a
lands have high steps, the piston should be re-
light coat of engine oil to the journals and bearings.
placed.
Install the rear main bearing cap. Install all bearing
2. Unless new pistons are installed, be sure to
caps except the thiust bearing cap. Be sure that main
I
install the pistons in the cylinders from which they
bearing caps are installed in original locations.
were removed. The numbers on the connecting rod
Tighten the bearing cap bolts to specifications.
and bearing cap must be on the same side when in-
10. Install the thrust bearing cap with bolts fin-
stalled in the cylinder bore. If a connecting rod is
ger-tight.
ever transposed from one engine or cylinder to an-
11. Pry the crankshaft forward against the thrust
other, new bearings should be fitted and the connect-
surface of upper half of bearing.
ing rod should be numbered to correspond with the *
12. Hold the crankshaft forward and pry the thrust
new cylinder number. The notch on the piston head
bearing cap to the rear. This aligns the thrust sur-
goes toward the front of the engine.
faces of both halves of the bearing.
3. Install all of the rod bearing inserts into the
13. Retain the forward pressure on the crankshaft.
rods and caps.
Tighten the cap bolts to specifications.
4. Install the rings to the pistons. Install the oil
14. Measure the crankshaft end-play as follows:
control ring first, then the second compression ring
a. Mount a dial gauge to the engine block
and finally the top compression ring. Use a piston
and position the tip of the gauge to read from the
ring expander tool to aid in installation and to help
Fig. 266 Carefully pry the crankshafl Ez
and forth while reading the dial gauge for
end-play first rod journal to the bottom of its stroke.
Pistons and Connecting Rods
4. Install the lower main bearing inserts in bear-
ing caps.
5. Clean the mating surfaces of block and rear
main bearing cap.
6. Carefully lower the crankshaft into place. Be
careful not to damage bearing surfaces.
7. Check the clearance of each main bearing by
using the following procedure:
a. Place a piece of Plastigage@ or its equiva-
lent, on bearing surface across full width of bear-
ing cap and about V4 in. off center.
b. Install cap and tighten bolts to specifica-
tions. Do not turn crankshaft while Plastigage@ is
in place.
c. Remove the cap. Using the supplied Plasti-
gage@ scale, check width of Plastigage@ at
widest point to get maximum clearance. Differ-
ence between readings is taper of journal.
d. If clearance exceeds specified limits, try a
0.001 in. or 0.002 in. undersize bearing in com-
bination with the standard bearing. Bearing clear-
ante must be within specified limits. If standard
and 0.002 in. undersize bearing does not bring
clearance within desired limits, refinish crank-
shaft journal, then install undersize bearings. crankshaft end.
b. Carefully pry the crankshaft toward the rear
of the engine and hold it there while you zero the
gauge.
c. Carefully pry the crankshaft toward the
front of the engine and read the gauge.
d. Confirm that the reading is within specifi-
cations. If not, install a new thrust bearing and
repeat the procedure. If the reading is still out of
specifications with a new bearing, have a ma-
chine shop inspect the thrust surfaces of the
crankshaft, and if possible, repair it.
15. Rotate the crankshaft so as to position the
# See Figures 269, 270,271, and 272
1. Before installing the piston/connecting rod
assembly, oil the pistons, piston rings and the cylin-
der walls with light engine oil. Install connecting rod
bolt protectors or rubber hose onto the connecting
rod bolts/studs. Also perform the following:
a. Select the proper ring set for the size cylin-
der bore.
b. Position the ring in the bore in which it is
going to be used.
c. Push the ring down into the bore area
where normal ring wear is not encountered.
d. Use the head of the piston to position the
ring in the bore so that the ring is square with
the cylinder wall. Use caution to avoid damage to
the ring or cylinder bore.
e. Measure the gap between the ends of the
ring with a feeler gauge. Ring gap in a worn
cylinder is normally greater than specification. If
the ring gap is greater than the specified limits,
try an oversize ring set.
f. Check the ring side clearance of the com-
pression rings with a feeler gauge inserted be-
tween the ring and its lower land according to
specification. The gauge should slide freely
around the entire ring circumference without
binding. Any wear that occurs will form a step at reduce the chance of breakage.
5. Make sure the ring gaps are properly spaced
around the circumference of the piston. Fit a piston
ring compressor around the piston and slide the pis-
ton and connecting rod assembly down into the
cylinder bore, pushing it in with the wooden hammer
handle. Push the piston down until it is only slightly
below the top of the cylinder bore. Guide the con-
netting rod onto the crankshaft bearing journal care-
fully, to avoid damaging the crankshaft.
6. Check the bearing clearance of all the rod
bearings, fitting them to the crankshaft bearing jour-
nals. Follow the procedure in the crankshaft installa-
tion above.
7. After the bearings have been fitted, apply a
light coating of assembly oil to the journals and bear-
ings.
8. Turn the crankshaft until the appropriate
bearing journal is at the bottom of its stroke, then
push the piston assembly all the way down until the
connecting rod bearing seats on the crankshaft jour-
nal. Be careful not to allow the bearing cap screws to
strike the crankshaft bearing journals and damage
them.
9. After the piston and connecting rod assem-
blies have been installed, check the connecting rod
side clearance on each crankshaft journal.
10. Prime and install the oil pump and the oil
pump intake tube.
11. Install the auxiliary/balance shaft(s)/assem-
bly(ies).
Cylinder Head(S)
1. Install the cylinder head(s) using new gaskets.
2, Install the timing sprockets/gears and the
belt/chain assemblies.
Engine Covers and Components
Install the timing cover(s) and oil pan. Refer to
your notes and drawings made prior to disassembly
and install all of the components that were removed.
Install the engine into the vehicle.

4-10 DRIVEABILITYAND EMISSIONS CONTROLS
I
OPERATION
The Engine Coolant Temperature (ECT) sensor re-
sistance changes in response to engine coolant tem-
perature. The sensor resistance decreases as the
coolant temperature increases, and increases as the
coolant temperature decreases. This provides a refer-
ence signal to the PCM, which indicates engine
coolant temperature. The signal sent to the PCM by
the ECT sensor helps the PCM to determine spark-
advance, EGR flow rate, air/fuel ratio, and engine
temperature. The ECT is a two wire sensor, a 5volt
3. Place the temperature sensing portion of the
sensor into a pan of hot water. Use a thermometer to
monitor the water temperature.
4. Measure the resistance across the sensor ter-
minals while the sensor is in the water. Comoare ob- Fig. 47 Another method of testing the EC1 Fig. 50 Use a deep socket and an extension
is to submerge it in cold or hot water and to reach the ECT sensor. 1 ,
reference signal is sent to the sensor and the signal
return is based upon the change in the measured re-
sistance due to temperature. 1 check resistance
TESTING
ti See Figures 45, 46, 47, and 48
1. Drain the engine coolant to a level below the
intake manifold.
2. Disconnect the sensor wiring harness and re-
move the coolant temperature sensor from the en-
gine.
Fig. 48 The ECT can be monitored with an
tained reading to specifications: ’
93154pos Fig. 45 Unplug the ECT sensor electrical
connector
1 soracross the two sensor pins g3154p30 Fig 48 Test the resistance of the ECT sen-
89574PlO
89574Pll
Fig. 51 . . .
then remove the ECT sensor
from the thermostat housing
a. Water temperature of 32°F (0°C~5.1-6.5
kilo-ohms present
b. Water temperature of 68°F (2O”C)--
2.1-2.7 kilo-ohms present
c. Water temperature of 104°F (4O”C)---
0.9-l .3 kilo-ohms present
d. Water temperature of 176°F (8O”Ck,
0.26-0.36 kilo-ohms present
5. If the resistance differs greatly from standard
value, replace the sensor.
REMOVAL &INSTALLATION
u See Figures 49, 50, 51, and 52
1. Disconnect the negative battery cable. Fig. 52 Before installation, coat the threads
Iolant to a level below the 2. Drain the engine c(
intake manifold.
3. Unplug1 the sensor wiring harness,
4. Unthreac
d and remove the sensor from the en-
gine.
To install:
5. Coat the threads of the sensor with a suitable
sealant and thread into the housing.
6. Tighten the sensor to 22 ft. Ibs. (30 Nm).
7. Refill the cooling system to the proper level.
8. Attach the electrical connector to the sensor
securely. appropriate and Data-stream capable scan 1
1
tnnl
9. Connect the negative battery cable.
Fig. 49 Unplug the ECT sensor electrical
---..^-s-- The Intake Air Temperature (IAT) sensor det
mines the air temnerature enterinn the! intake n er-
- ._ r_ -.-._ _. ._. J . _ ..-. ._
iani- OPERATION
+ See Figure 53

DRIVEABILITYAND EMISSIONS CONTROLi 4-11
fold. Resistance changes in response to the ambient
air temperature. The sensor has a negative tempera-
ture coefficient. As the temperature of the sensor
rises the resistance across the sensor decreases. Thil
provides a signal to the PCM indicating the tempera-
ture of the incoming air charge. This sensor helps the
PCM to determine spark timing and air/fuel ratio. In-
formation from this sensor is added to the pressure
sensor information to calculate the air mass being
sent to the cylinders. The IAT receives a 5-volt refer-
ence signal and the signal return is based upon the
change in the measured resistance due to tempera-
ture.
TESTING
b See Figures 54, 55, 56, 57, and 58
Fig. 54 Testing the resistance of the IAT
sensor across the two sensor pins
Fig. 55 The IAT sensor can be monitored
with an appropriate and Data-stream capa-
ble scan tool
~1 b. Sensor temperature of 68°F (2O”C)--‘ 2.>3.0 kilo-ohms c. Sensor temperature of 176°F (SO*C)-
0.30-0.42 kilo-ohms
5. Measure the sensor resistance while heating
the sensor area with a hair dryer. As the temperature
of the sensor increases, sensor resistance should be-
come smaller.
6. If the measured resistance deviates from the
standard value or the resistance remains unchanged,
replace the air flow sensor assembly.
1 REMOVAL&INSTALLATION
The IAT sensor is part of the Mass Air Flow (MAF)
sensor. The IAT sensor cannot be replaced sepa-
rately. Refer to MAF sensor removal and installation
in this section.
- OPERATION a9574g72 Fig. 56 IAT sensor terminal identification;-
1990-93 Galant The Mass Air Flow (MAF) sensor directly mea-
lres the mass of air being drawn into the engine.
I ?he sensor output is used to calculate injector pulse
width. The MAF sensor is what is referred to as a
“hot-wire sensor”. The sensor uses a thin platinum
wire filament, wound on a ceramic bobbin and coated
with glass, that is heated to 417°F (200°C) above the
amh+en+ nir +PmnPrfijre and subiected to the intake
..I._ ~ ..-.. .“..‘r-,u.. ai mow stream. A “cold-wire” is used inside the MAF
sensor resuirance wnoe nearmg ir wnn a 1
hair drier ‘hat melt: IS al I~“< ,“.., lvllQ UtiLnbtill ,,,=
tnd GND terminals of the MAF sensor connec-
tor. If voltaae is not within specification, check power
1. Detach the air flow sensor electrical connector.
2. Measure the resistance between terminals No.
4 and No. 6 of the electrical connector, except on the
2.OL DOHC turbo engine.
3. ff equipped with the 2.OL DOHC turbo engine,
measure the resistance between terminals No. 6 and
No. 8 of the sensor electric connector.
4. Compare test readings to the following specifi-
cations:
a. Sensor temperature of 32°F (O“C)--
5.3-6.7 kilo-ohms and groundcircuits and repair as necessary.
verify that there is at least 4.5 volts between the SIG 3. With the ignition key ON, and,the engine ON,
and GND terminals of the MAF sensor connector. If
voltage is not within specification, check power and
ground circuits and repair as necessary.
4. With the ignition key ON, and the engine ON,
check voltage between GND and SIG RTN terminals.
Voltage should be approximately 0.34-l .96 volts. If
voltage is not within specification, the sensor may be
faulty.
/ sensor to determine the ambient air temperature.
Battery voltage, a reference signal, and a ground
signal from the PCM are supplied to the MAF sensor.
rho ~pn**r rp+++rns a signal proportionate to the cur-
re. The increased airflow across the
s a cooling fan, lowering the resis-
mo more current to maintain the tem- tance and requir
e^-‘.._^ ^I LL^
I
Intake air temper- pe~a+ure UI me wire. The increased current is mea- aturf sensor sured by the voltage in the circuit, as current
increases, voltage increases. As the airflow increases
the signal return voltage of a normally operating MAF
sensor will increase.
, ~~1 TESTING - II ire” at the re-
89574g74 Fig. 58 Measure the intake air temperature
-----_ ---1-a---- L..- L--1. . . .*a 1. Using a multimeter, check for voltage by back-
nrr\hinn +hn MAF sensor connector.
the ignition key ON, and the engine OFF, .^-^ :- -’ ‘.txt In E; \mltr hahrman tha veriry t
BAT-T i

DRIVEABILITYAND EMISSIONS CONTROiS 4-13
4. If the voltaoe check in sbo 3 was OK. then
check the voltage-between GND’and SIG RTN termi-
nals and suddenly depress the accelerator, the volt-
age should rise and stay at 2.4 volts. If the voltage
OPERATION does not stay at 2.4 volts, replace the MAP sensor.
REMOVAL&INSTALLATION '
ti See Figures 68, 69, and 70
1. Disconnect the negative bat lery cable.
2. Detach the connector for thl e MAP sensor.
3. Remove the sensor mountir ig screws.
4. Lift the sensor up and remove it from the intake
manifold. The Throttle Posii
ti-* \*. Inn ITPl smsnr is 8 Dotentiome- , WI...,". *., . ter that provides a si gnal to the PCM that is directly
proportion: il to the throttle plate position. The TP
sensor is rr iounted on the side of the throttle body
and is connected to the throttle plate shaft. The TP
sensor monitors throttle plate movement and posi-
tion, and transmits an appropriate electrical signal to
the PCM. These signals grp IIQX-I hv rho PCM to ad-
just the air/flnI mivtlI “-- ------li
5. The installation is the reverse of removal. WI I dLfUl U full throttle The TP c
UyI ,,,,,,,:re, spark timing and EGR opera-
ng to engine load at idle, part throttle, or
The TP sensor is not adjustable.
..-
lensor receives a 5 volt reference signal
and a ground circuit from the PCM. A return signal
circuit is connected to a wiper that runs on a resistor
internally on the sensnr ThP fmth@r rho throttle is
opined the winnr mr oP -*lY”, .I,” ..,y’V, 111 Jves along the resistor, at wide
en throttle, the wiper essentially creates a loop be-
tween the reference signal and the signal return re-
turning the full or nearly full 5 volt signal back to the
PCM. At idle, the signal return should be approxi-
rnz
rtely 0.9 volts.
TF
iSTING
) See Figures 71 ,72, 73, and 74
1. With the engine OFF and the ignition ON,
check the voltage at the signal return circuit of the TP
sensor bv carefullv backorobina the connector using
aDVOM: . ” Fig. 68 Detach the electrical connector from
the MAP sensor
taining bolts . . . WMp,l
Fig. 71 Testing the SIG circuit to the TP sen-
then remove the sensor from
the intake manifold. Inspect the tip of the
sensor and replace if damaged or plugged Fig. 72 Testing the SIG RTN circuit of the
TP sensor
sm4p10 I Fig. 73 Testing the operation of the poten- 1
tiometer inside the TP sensor while slowly 1
opening the throttle
Fig. 74 The TP sensor can be monitored with
an appropriate and Data-stream capable
2. Voltage should be between 0.2 and 1.4 volts at
idle.
3. Slowlv move the throttle oullev to the Wide
Open Throttle (WOT) position and watch the voltage
on the DVOM. The voltage should slowly rise to
slightly less than 4.8 volts at WOT.
4. If no voltage is present, check the wiring har-
ness for supply voltage (5.0 volts) and ground (0.3
volts or less), by referring to your corresponding
wiring guide. If supply voltage and ground are pre-
sent, but no output voltage from TP, replace the TP
sensor. If supply voltage and ground do not meet
specifications, make necessarv reoairs to the harness
or PCM.
,
REMOVAL&INSTALLATION
# See Figures 75 and 76
1. Disconnect the negative battery cable.
2. Disconnect the wiring harness from the TP
sensor.
3. Remove the two sensor mounting screws, then
pull the TP sensor off of the throttle shaft.
To install:
4. Carefully slide the rotary tangs on the sensor
into position over the throttle shaft. then rotate the
sensor clockwise to the installed position.

DRIVEABILITYAND EMISSIONS CONTROLS 4-27
WITHOUTASCANTOOL
8 See Figure 87. 1. Remove the under dash cover, if equipped.
2. Attach an analoa voltmeter between the on-
board diagnostic outpit terminal of the data link con-
nector and the ground terminal
3. Turn the ignition switch ON.
4. Read the on-board diagnostic output pattern
from the voltmeter and record.
5. Diagnose and repair the faulty components as
required.
OBD OUTPUT
[TERMINAL
tic (OBO) output and ground terminal loca-
tions on the data link connector
6. Erase the trouble code.
7. Turn the ignition swatch ON, and read the di-
agnostic trouble codes, checking that a normal code
is output.
*To erase diagnostic trouble codes with a
scan tool, follow the directions given by the
tools manufacturer.
1. Turn the ignition switch OFF. 2. Disconnect the negative battery cable from the
battery for 1 minute or more, then reattach it.
3. Turn ON the ignition switch and read the diag-
nostic trouble codes checking that a normal code is
output.
Code 11 Oxygen sensor Code 12 Air flow sensor Code 13 Intake Air Temperature Sensor Code 14 Throttle Position Sensor (TPS) Code 15 SC Motor Position Sensor (MPS)
Code 21 Engine Coolant Temperature Sensor Code 22 Crank angle sensor Code 23 No. 1 cylinder TDC (camshaft position)
Sensor
Code 24 Vehicle speed sensor Code 25 Barometric pressure sensor Code 31 Knock sensor (KS) Code 32 Manifold pressure sensor Code 36 Ignition timmg adjustment signal Code 39 Oxygen sensor (rear - turbocharged) Code 41 Injector Code 42 Fuel pump Code 43 EGR-California Code 44 Ignition Coil; power transistor unit (No.
1 and No. 4 cvlinders) on 3.OL
Code 62 ignition Coil; power transistor unit (No.
2 and No. 5 cvlinders) on 3.OL
Code 53 ignition Coil; power transistor unit (No.
3 and No. 6 cylinders) on 3.OL
Code 55 AC valve position sensor Code 59 Heated oxygen sensor Code 61 Transaxle control unit cable (automatic
transmission)
Code 62 Warm-up control valve position sensor
(non-turbo)
The Powertrain Control Module (PCM) is given
responsibrlity for the operation of the emission con-
trol devices, cooling fans, ignition and advance and
in some cases, automatic transaxle functions. Be-
cause the PCM oversees both the ignition timing and
the fuel injection operation, a precise air/fuel ratio
will be maintained under all operating conditions,
The PCM is a microprocessor, or small computer,
which receives electrical inputs from several sensors,
switches and relays on and around the engine.
Based on combinations of these inputs, the PCM
controls outputs to various devices concerned with
engine operation and emissions. The control module
relies on the signals to form a correct picture of cur-
rent vehicle operation. If any of the input signals is
incorrect, the PCM reacts to whatever picture is
painted for it. For example, if the coolant temperature
sensor is inaccurate and reads too low, the PCM may
see a picture of the engine never warming up. Conse-
quently, the engine settings will be maintained as if
the engine were cold. Because so many inputs can
affect one output, correct diagnostic procedures are
essential on these systems,
One part of the PCM is devoted to monitoring
both input and output functions within the system.
This ability forms the core of the self-diagnostic sys-
tem. If a problem is detected within a circuit, the con-
trol module will recognize the fault, assign it a Diag-
nostic Trouble Code (DTC), and store the code in
memory. The stored code(s) may be retrieved during
diagnosis. While the OBD-II system is capable of recognizing
many internal faults, certain faults WIII not be recog-
nized. Because the control module sees only electri-
cal signals, it cannot sense or react to mechanical or
vacuum faults affecting engine operation. Some of
these faults may affect another component which will
set a code. For example, the PCM monitors the out-
put signal to the fuel injectors, but cannot detect a
partially clogged injector. As long as the output dri-
ver responds correctly, the computer will read the
system as functioning correctly. However, the im-
proper flow of fuel may result in a lean mixture. This
would, in turn, be detected by the oxygen sensor and
noticed as a constantly lean signal by the PCM. Once
the signal falls outside the pre-programmed limits,
the control module would notice the fault and set a
trouble code.
Additionally, the OBD-II system employs adaptive
fuel logic. This process is used to compensate for
normal wear and variability within the fuel system.
Once the engine enters steady-state operation, the
control module watches the oxygen sensor signal for
a bias or tendency to run slightly rich or lean. If such
a bias is detected, the adaptive logic corrects the fuel
delivery to bring the air/fuel mixture towards a cen-
tered or 14.7:1 ratio. This compensating shift is
stored In a non-volatile memory which is retained by
battery power even with the ignition switched
OFF. The correction factor is then available the next time
the vehicle is operated.
WITHASCANTOOL
8 See Figures 88, 89, 90, and 91
The Diagnostic Link Connector (DLC), under the
left-hand side of the instrument panel, must be lo-
cated to retrieve any OTC’s
Reading the control module memory is on of the
first steps in OBD II system diagnostics. This step
should be initially performed to determine the general
nature of the fault. Subsequent readings will deter-
mine if the fault has been cleared.
Reading codes can be performed by any of the
methods below:
l Read the control module memory with the
Generic Scan Tool (GST)
l Read the control module memory with the ve-
hicle manufacturers specific tester
To read the fault codes, connect the scan tool or
tester according to the manufacturers instructions.
Follow the manufacturers specified procedure for
reading the codes.
WITHOUTASCANTOOL
8 See Figure 92
The Diagnostic Link Connector (DLC), under the
left-hand side of the instrument panel, must be lo-
cated to retrieve any DTC’s.

4-28 DRIVEABILITYAND EMISSIONS CONTROLS
Fig. 88 Plug the scan tool into the DLC un-
Fig. 89 Follow the directions on the scan
der the driver’s side of the instrument panel
tool screen to retrieve the DTC’s 3. Locate the Diagnostic Link Connector (DLC),
which is usually under the left-hand side of the in-
strument panel.
4. Start the engine and drive the vehicle until the
transaxle goes into the failsafe mode.
5. Park the vehicle, but do not turn the ignition
OFF. Allow it to idle.
6. Attach a voltmeter (analog or digital) to the test
terminals on the Diagnostic Link Connector (DLC).
The negative lead should be attached to terminal 4
and the positive lead to terminal 1.
7. Observe the voltmeter and count the flashes
(or arm sweeps if using an analog voltmeter); note
the applicable codes.
- 8. After all of the DTC(s) have been retrieved, fix
the applicable problems, clear the codes, drive the
vehicle, and perform the retrieval procedure again to
ensure that all of the codes are gone.
WITHASCANTOOL
Control module reset procedures are a very im-
portant part of OBD II System diaqnostics.
This step should be done at the end of any fault
code repair and at the end of any driveability repair.
Clearing codes can be performed by any of the
Fig. 90 in this case, we would choor- A ’ ma*-. . . * .
Trouble Codes to retrieve the DTC’s
-.- -
A mere mar
. . methods below: l Clear the control module memory with the
se l-
I I ng. vi me rtim In mts venicie contains no Generic Scan Tool (GST) l DTC’S Clear the control module memory with the ve-
L’-‘m iufacturer’s specific tester
The Federal government decided that it was time
to create a standard for vehicle diagnostic systems
codes for ease of servicing and to insure that certain
of the vehicle’s systems were being monitored for
emissions purposes. Since OBD II codes are stan-
dardized (they all contain one letter and four num-
bers), they are easy to decipher.
The OBD II system in the Mitsubishi models is de-
signed so that it will flash the DTC’s out on a volt-
meter (even though a scan tool is better). However,
the first two characters of the code are not used. This
is because the transaxle is a part of the powertrain, so
all transaxle related codes will begin with a P. Also, *The MIL will may also be de-activated for
some codes if the vehicle completes three
consecutive trips without a fault detected
with vehicle conditions similar to those pre-
sent during the fault.
WITHOUTASCAN TOOL
If there are still codes p
resent, either the codes
were not properly cleared f
:Are the codes identical to
those flashed out previous
I$‘), or the underlying
problem is still there (Are I
only some of the codes the
same as oreviouslv?).
since there are no overlapping numbers between SAE
and Mitsubishi codes, the second digit is also not
necessary.
The system flashes the codes o
ut ma series of
flashes in
three nmm mh nrnlll -- J.-lr-, ---.. ~.--
p corresponding to
one of the
three last diaits of the OBD II code. There-
fore, Code WJJ wuuw UC:
IIKWAJ WI III XVWI flashes, followed by five flashes, then by three
flashes. Each group of flashes is se
pause. All of the flashes are of the (
witi the or$, nvrontinn hoinn mm sented by z
long flash,
(shorted Tt SWIWI LIIW. rparated by a brief
;ame duration,
88, “rw”I.‘L’“‘I uv,,,y LUI”.
Zero is repre-
1 long flash. Therefore, seven flashes, one
two flashes would indicate a PO702 code
3 nnmn^r ,.:*....:I I r
SCANTOOLCODES
. YYY” I ‘I” I cuI”I”.J PO100 Mass or Volume Air Flow Circuit Malfunc-
Lb
non
PO101 Mass orVolume Air Flow Circuit
Range/Performance Problem
PO102 Mass or Volume Air Flow Circuit Low In-
Put
.
To retrieve the codes, perform the following: PO103 Mass or Volume Air Flow Circuit High In-
i Put
1. Perform the preliminary inspection, located PO104 Mass or Volume Air Flow Circuit Intermit-
-;
Vehicle speed es446e35 Fig. 92 For OBO ii code retrieval without us-
ing a scan tool on Mitsubishi models, con-
nect the DVOM and jumper wire as shown
In 1996, all Mitsubishi switched from an arbitrary
code listing and format, to the federally regulated On
Board Diagnostics 2nd Generation (OBD II) code sys-
tern. Normally, OBD II equipped vehicles do not have
the option of allowing the person servicing the vehi-
cle to flash the codes out with a voltmeter; usually a
scan tool is necessary to retrieve OBD II codes. Mit-
subishi, however, does provide this option, earlier in this section. This is very important, since a
loose or disconnected wire, or corroded connector
terminals can cause a whole slew of unrelated DTC’s
to be stored by the computer; you will waste a lot of
time performing a diagnostic “goose chase.”
2. Grab some paper and a pencil or pen to write
down the DTC’s when they are flashed out. tent
PO105 Manifold Absolute Pressure/Barometric
Pressure Circuit Malfunction
PO106 Manifold Absolute Pressure/Barometric
Pressure Circuit Range/Performance Problem
PO107 Manifold Absolute Pressure/Barometric
Pressure Circuit Low Input

DRIVEABILITYAND EMISSIONS CONTROLS 4-29
PO108 Manifold Absolute Pressure/Barometric
Pressure Circuit High Input
PO109 Manifold Absolute Pressure/Barometric
Pressure Circuit Intermittent
PO110 intake Air Temperature Circuit Malfunction
PO111 Intake Air Temperature Circuit Range/Per-
formance Problem
PO112 Intake Air Temperature Circuit Low Input
PO113 Intake Air Temoerature Circuit Hiah lnout
PO114 Intake Air Temberature Circuit lnt&miitent
PO115 Engine Coolant Temperature Circuit Mal-
function -
PO116 Engine Coolant Temperature Circuit
Range/Performance Problem
PO117 Engine Coolant Temperature Circuit Low
Input
PO118 Engine Coolant Temperature Circuit High
Input
PO119 Engine Coolant Temperature Circuit Inter-
mittent
PO120 Throttle Position Sensor/Switch “A” Cir-
cuit Malfunction
PO121 Throttle Position Sensor/Switch “A” Cir-
cuit Range/Performance Problem
PO122 Throttle Position Sensor/Switch “A” Cir-
cuit Low Input
PO123 Throttle Position Sensor/Switch “A” Cir-
cuit High Input
PO124 Throttle Position Sensor/Switch “A” Cir-
cuit Intermittent
PO125 Insufficient Coolant Temperature For
Closed Loop Fuel Control
PO126 Insufficient Coolant Temperature For Sta-
ble Operation
PO130 02 Circuit Malfunction (Bank no. 1 Sen-
sor no. 1)
PO131 02 Sensor Circuit Low Voltage (Bank no.
1 Sensor no. 1)
PO132 02 Sensor Circuit High Voltage (Bank no.
1 Sensor no. 1)
PO133 02 Sensor Circuit Slow Response (Bank
no. 1 Sensor no. 1)
PO134 02 Sensor Circuit No Activity Detected
(Bank no. 1 Sensor no. 1)
PO135 02 Sensor Heater Circuit Malfunction
(Bank no. 1 Sensor no. 1)
PO136 02 Sensor Circuit Malfunction (Bank no.
1 Sensor no. 2)
PO137 02 Sensor Circuit Low Voltage (Bank no.
1 Sensor no. 2)
PO138 02 Sensor Circuit High Voltage (Bank no.
1 Sensor no. 2)
PO139 02 Sensor Circuit Slow Response (Bank
no. 1 Sensor no. 2)
PO140 02 Sensor Circuit No Activity Detected
(Bank no. 1 Sensor no. 2)
PO141 02 Sensor Heater Circuit Malfunction
(Bank no. 1 Sensor no. 2)
PO142 02 Sensor Circuit Malfunction (Bank no.
1 Sensor no. 3)
PO143 02 Sensor Circuit Low Voltage (Bank no.
1 Sensor no. 3)
PO144 02 Sensor Circuit High Voltage (Bank no.
1 Sensor no. 3)
PO145 02 Sensor Circuit Slow Response (Bank
no. 1 Sensor no. 3)
PO146 02 Sensor Circuit No Activity Detected
(Bank no. 1 Sensor no. 3)
PO147 02 Sensor Heater Circuit Malfunction
(Bank no. 1 Sensor no. 3)
PO150 02 Sensor Circuit Malfunction (Bank no.
2 Sensor no. 1) PO151 02 Sensor Circuit Low Voltage (Bank no.
2 Sensor no. 1)
PO152 02 Sensor Circuit High Voltage (Bank no.
2 Sensor no. 1)
PO153 02 Sensor Circuit Slow Response (Bank
no. 2 Sensor no. 1)
PO154 02 Sensor Circuit No Activity Detected
(Bank no. 2 Sensor no. 1)
PO155 02 Sensor Heater Circuit Malfunction
(Bank no. 2 Sensor no. 1)
PO156 02 Sensor Circuit Malfunction (Bank no.
2 Sensor no. 2)
PO157 02 Sensor Circuit Low Voltage (Bank no.
2 Sensor no. 2)
PO158 02 Sensor Circuit High Voltage (Bank no.
2 Sensor no. 2)
PO159 02 Sensor Circuit Slow Response (Bank
no. 2 Sensor no. 2)
PO160 02 Sensor Circuit No Activity Detected
(Bank no. 2 Sensor no. 2)
PO161 02 Sensor Heater Circuit Malfunction
(Bank no. 2 Sensor no. 2)
PO162 02 Sensor CircuitMalfunction(8ank
no.2 Sensorno.3)
PO16302 Sensor Circuit Low Voltage
(Bankno. Sensorno.3)
PO16402 Sensor Circuit HighVoltage
(Bankno. Sensorno.3)
PO16502 Sensor Circuit Slow Response
(Bankno. Sensorno.3)
PO166 02 Sensor Circuit No Activity De-
tected(Bankno.2 Sensorno.3)
PO16702 SensorHeaterCircuitMalfunc-
tion(Bank no.2 Sensorno.3)
PO170 Fuel Trim Malfunction (Bank no. 1 )
PO171 System Too Lean (Bank no. 1 )
PO172 Svstem Too Rich (Bank no 1 )
PO173 F;el Trim Malfundtion (Bank io. 2 )
PO174 System Too Lean (Bank no 2 )
PO175 System Too Rich (Bank no. 2 )
PO176 Fuel Composition Sensor Circuit Mal-
function
PO177 Fuel Composition Sensor Circuit
Range/Performance
PO178 Fuel Composition Sensor Circuit Low In-
put
PO179 Fuel Composition Sensor Circuit High In-
put
PO180 Fuel Temperature Sensor “A” Circuit Mal-
function
PO181 Fuel Temperature Sensor “A” Circuit
Range/Performance
PO182 Fuel Temperature Sensor “A” Circuit Low
Input
PO183 Fuel Temperature Sensor “A” Circuit High
Input
PO184 Fuel Temperature Sensor “A” Circuit Inter-
mittent
PO185 Fuel Temperature Sensor “B” Circuit Mal-
function
PO186 Fuel Temperature Sensor “B” Circuit
Range/Performance
PO187 Fuel Temperature Sensor “B” Circuit Low
Input
PO188 Fuel Temperature Sensor “B” Circuit High
Input
PO189 Fuel Temperature Sensor “B” Circuit Inter-
mittent
PO190 Fuel Rail Pressure Sensor Circuit Mal-
funchon
PO191 Fuel Rail Pressure Sensor Circuit
Range/Performance PO192 Fuel Rail Pressure Sensor Circuit Low In-
put
PO193 Fuel Rail Pressure Sensor Circuit High In-
put
PO194 Fuel Rail Pressure Sensor Circuit Intermit-
tent
PO195 Engine Oil Tempetature Sensor Malfunc-
tion
PO198 Engine Oil Temperature Sensor
Range/Performance
PO197 Engine Oil Temperature Sensor Low
PO198 Engine Oil Temperature Sensor High
W199 Engine Oil Temperature Sensor Intermit-
tent
PO200 Injector Circuit Malfunction
PO201 Injector Circuit Malfunction-Cylinder
no. 1
PO202 Injector Circuit Malfunction-Cylinder
no. 2
PO203 Injector Circuit Malfunction-Cylinder
no. 3
PO204 Injector Circuit Malfunction-Cylinder
no. 4
PO205 Injector Circuit Malfunction-Cylinder
no. 5
PO206 Injector Circuit Malfunction-Cylinder
no. 6
PO214 Cold Start Injector no. 2 Malfunction
PO215 Engine Shutoff Solenoid Malfunction
PO218 Injection Timing Control Circuit Malfunc-
tion
PO217 Engine Over Temperature Condition
PO218 Transmission Over Temperature Condition
PO219 Engine Over Speed Condition
PO220 Throttle Position Sensor/Switch ‘9” Cir-
cuit Malfunction
PO221 Throttle Position Sensor/Switch “B” Cir-
cuit Range/Performance Problem
PO222 Throttle Position Sensor/Switch “B” Cir-
cuit Low Input
PO223 Throttle Position Sensor/Switch “B” Cir-
cuit High Input
PO224 Throttle Position Sensor/Switch “B” Cir-
cuit Intermittent
PO225 Throttle Position Sensor/Switch “C” Cir-
cuit Malfunction
PO226 Throttle Position Sensor/Switch “C” Cir-
cuit Range/Performance Problem
PO227 Throttle Position Sensor/Switch “c” Cir-
cuit Low Input
PO228 Throttle Position Sensor/Switch “C” Cir-
cuit High Input
PO229 Throttle Position Sensor/Switch “C” Cir-
cuit Intermittent
PO230 Fuel Pump Primary Circuit Malfunction
PO231 Fuel Pump Secondary Circuit Low
PO232 Fuel Pump Secondary Circuit High
PO233 Fuel Pump Secondary Circuit Intermittent
PO261 Cylinder no. 1 Injector Circuit Low
PO262 Cylinder no. 1 Injector Circuit High
PO263 Cylinder no. 1 Contribution/Balance Fault
PO264 Cvlinder no. 2 lniector Circuit Low
PO265 Cylinder no. 2 Injector Circuit High
PO266 Cylinder no. 2 Contribution/Balance Fault
PO267 Cylinder no. 3 Injector Circuit Low
PO268 Cylinder no. 3 Injector Circuit High
PO269 Cylinder no. 3 Contribution/Balance Fault
PO270 Cylinder no. 4 Injector Circuit Low
PO271 Cvlinder no. 4 lniector Circuit Hiah
PO272 Cylinder no. 4 CbntributionlBalaice Fault
PO273 Cylinder no. 5 Injector Circuit Low
PO274 Cylinder no. 5 Injector Circuit High

FUELSYSTEM 513
l Always replace worn fuel fitting O-rings with
new. Do not substitute fuel hose or equivalent, where
I
The Multi-Point Injection (MPI) system is electroni-
rally controlled by the Engine Control Module (ECM),
based on data from various sensors. The ECM controls
the fuel flow, idle speed and ignition timing. fuel pipe is installed.
Fuel is supplied to the injectors by an electric in-
tank fuel pump and is distributed to the respective in-
jectors via the main fuel pipe. The fuel pressure ap-
plied to the injector is constant and higher than the
pressure in the intake manifold. The pressure is con-
trolled by the fuel pressure regulator. The excess fuel
is returned to the fuel tank through the fuel return pipe.
When an electric current flows in the injector, the
injector valve is fully opened to supply fuel. Since the
fuel pressure is constant, the amount of the fuel in-
jetted from the injector into the manifold is increased
or decreased in proportion to the time the electric
current flows. Based on ECU signals, the injectors in-
ject fuel to the cylinder manifold ports in firing order. Fuel injection systems remain under pres-
sure after the engine has been turned OFF.
Properly relieve fuel pressure before discon-
neeting any fuel lines. Failure to do so may
result in fire or personal injury.
1. Turn the ignition to the OFF position.
2. Loosen the fuel filler cap to release fuel tank
pressure.
I
The flow rate of the air drawn through the air
cleaner is measured by the air flow sensor. The air
enters the air intake plenum or manifold through the
throttle body. In the intake manifold, the air is mixed
with the fuel from the injectors and is drawn into the
cylinder, The air flow rate is controlled according to
the degree of the throttle valve and the servo motor
openings. The system is monitored through a num-
ber of sensors which feed information on engine con-
ditions and requirements to the ECM. The ECM cal-
culates the injection time and rate according to the
signals from the sensors,
Safety is the most important factor when perform-
ing not only fuel system maintenance but any type of
maintenance. Failure to conduct maintenance and re-
pairs in a safe manner may result in serious personal
injury or death. Maintenance and testing of the vehi-
cle’s fuel system components can be accomplished
safely and effectively by adhering to the following
rules and guidelines.
l To avoid the possibility of fire and personal in-
jury, always disconnect the negative battery cable un-
less the repair or test procedure requires that battery
voltage be applied.
l Always relieve the fuel system pressure prior to
disconnecting any fuel system component (injector,
fuel rail, pressure regulator, etc.), fitting or fuel line
connection. Exercise extreme caution whenever re- Observe all applicable safety precautions
when working around fuel. Whenever servic-
ing the fuel system, always work in a well
ventilated area. Do not allow fuel spray or va-
pors to come in contact with a spark or open
flame. Keep a dry chemical fire extinguisher
near the work area. Always keep fuel in a con-
tainer specifically designed for fuel storage;
also, always properly seal fuel containers to
avoid the possibility of fire or explosion.
3. For the Mirage, Diamante, and 1994-00
Galant, remove the rear seat cushion, then remove
the service cover and detach the fuel pump harness
connector.
4. For the 1990-93 FWD Galant, detach the fuel
pump harness connector located in the area of the
fuel tank. It may be necessary to raise the vehicle to
access the connector.
5. For the 1990-93 AWD Galant, remove the car-
pet from the trunk, locate the fuel tank wiring at the
pump access cover, then detach the wiring.
6. Start the vehicle and allow it to run until it
stalls from lack of fuel. Turn the key to the OFF posi-
tion.
7. Disconnect the negative battery cable, then at-
tach the fuel pump connector. Install the access .
cover, cushion or carpet as necessary.
8. Wrap shop towels around the fitting that is be-
ing disconnected to absorb residual fuel in the lines.
9. Place shop towels into proper safety container. Fig, 8 Detach the connector for the throttle
position (TP) sensor
93153ps5 Fig, 9 Remove the accelerator cable end
from the throttle lever
Fig. IO Remove the hose shown here from
lieving fuel system pressure to avoid exposing skin,
face and eyes to fuel spray. Please be advised that
fuel under pressure may penetrate the skin or any
part of the body that it contacts.
l Always place a shop towel or cloth around the
fitting or connection prior to loosening to absorb any
excess fuel due to spillage. Ensure that all fuel
spillage (should it occur) is quickly removed from
enginesurfaces. Ensure that all fuel soaked cloths or
towels are deposited into a suitable waste container.
l Always keep a dry chemical (Class B) fire ex-
tinguisher near the work area.
l Do not allow fuel spray or fuel vapors to come
into contact with a spark or open flame.
l Always use a backup wrench when loosening’
and tightening fuel line connection fittings. This will
prevent unnecessary stress and torsion to fuel line
piping. Always follow the proper torque specifica-
tions. REMOVAL &INSTALLATION
p See Figures 8 thru 18
1. Properly relieve the fuel system pressure as
outlined earlier in this section.
2. Drain the engine cooling system into a suit-
able container.
3. Matchmark the jocation of the adjuster bolt
on the accelerator cable mounting flange. This will
assure that the cable is installed in its original loca-
tion. Remove the throttle cable adjusting bolt and
disconnect the cable from the lever on the throttle
body. Position cable aside.

CHASSIS ELECTRiCAL 6-5
them. It is used for voltage and ground tests. To use voltmeter has a positive and a negative lead. To avoid
a 12 volt test light, connect the ground clip to a good damage to the meter, always connect the negative
ground and probe wherever necessary with the pick. lead to the negative (-) side of the circuit (to ground
The test light will illuminate when voltage is detected. or nearest the ground side of the circuit) and connect
This
does not necessarily mean that 12 volts (or any the positive lead to the positive(t) side of the circuit When diagnosing a specific problem, organized
troubleshooting is a must. The complexity of a mod-
particular amount of voltage) is present; it only (to the power source or the nearest power source).
means that some voltage is present. It is advisable Note that the negative voltmeter lead will always be ern automotive vehicle demands that you approach
before using the test light to touch its ground clip black and that the positive voltmeter will always be any problem in a logical, organized manner. There
and probe across the battery posts or terminals to some color other than black (usually red). are certain troubleshooting techniques, however,
which are standard:
make sure the light is operating properly.
l Ohmmeter-the ohmmeter is designed to read l Establish when the problem occurs. Does the
resistance (measured in ohms) in a circuit or compo-
nent. Most ohmmeters will have a selector switch problem appear only under certain conditions? Were
there any noises, odors or other unusual symptoms?
Do not use a test light to probe electronic ig- which permits the measurement of different ranges of
Isolate the problem area. To do this, make some sim-
nition, spark plug or coil wires. Never use a resistance (usually the selector switch allows the
multiplication of the meter reading by 10,100,1,000 ple tests and observations, then eliminate the sys-
pick-type test light to probe wiring on com- terns that are working properly. Check for obvious
puter controlled systems unless specifically and 10,000). Some ohmmeters are “auto-ranging”
which means the meter itself will determine which problems, such as broken wires and loose or dirty
instructed to do so. Any wire insulation that
scale to use. Since the meters are powered by an in- connections. Always check the obvious before as-
is pierced by the test light probe should be
ternal battery, the ohmmeter can be used like a self- suming something complicated is the cause.
taped and sealed with silicone after testing.
l Test for problems systematically to determine
powered test light. When the ohmmeter is connected,
the cause once the problem area is isolated. Are all
Like the jumper wire, the 12 volt test light is used current from the ohmmeter flows through the circuit
the components functioning properly? Is there power
to isolate opens in circuits. But, whereas the jumper or component being tested. Since the ohmmeter’s in-
ternal resistance and voltage are known values, the going to electrical switches and motors. Performing
wire is used to bypass the open to operate the load,
amount of current flow through the meter depends on careful, systematic checks will often turn up most
the 12 volt test light is used to locate the presence of
the resistance of the circuit or component being causes on the first inspection, without wasting time
voltage in a circuit. If the test light illuminates, there
tested. The ohmmeter can also be used to perform a checking components that have little or no relation-
is power up to that point in the circuit; if the test light ship to the problem.
does not illuminate, there is an open circuit (no continuity test for suspected open circuits. In using
the meter for making continuity checks, do not be
l Test all repairs after the work is done to make
power). Move the test light in successive steps back
concerned with the
actual resistance readings. Zero sure that the problem is fixed. Some causes can be
toward the power source until the light in the handle traced to more than one component, so a careful veri-
illuminates. The open is between the probe and a resistance, or any ohm reading, indicates continuity
fication of repair work is important in order to pick up
point which was previously probed. in the circuit, Infinite resistance indicates an opening
in the circuit. A high resistance reading where there additional malfunctions that may cause a problem to
The self-powered test light is similar in design to
should be none indicates a problem in the circuit. reappear or a different problem to arise. A blown
the 12 volt test light, but contains a 1.5 volt penlight
Checks for short circuits are made in the same man- fuse, for example, is a simple problem that may re-
battery in the handle. It is most often used in place of
ner as checks for open circuits, except that the circuit quire more than another fuse to repair. If you don’t
a multimeter to check for open or short circuits when look for a problem that caused a fuse to blow, a
power is isolated from the circuit (continuity test). must be isolated from both power and normal
ground. Infinite resistance indicates no continuity, shorted wire (for example) may go undetected.
The battery in a self-powered test light does not Experience has shown that most problems tend
provide much current. A weak battery may not pro- while zero resistance indicates a dead short.
to be the result of a fairly simple and obvious
vide enough power to illuminate the test light even I ’ cause, such as loose or corroded connectors, bad
when a complete circuit is made (especially if there is grounds or damaged wire insulation which causes a
high resistance in the circuit). Always make sure that Never use an ohmmeter to check the resis- short. This makes careful visual inspection of com-
the test battery is strong. To check the battery, briefly tance of a component or wire while there is ponents during testing essential to quick and accu-
touch the ground clip to the probe; if the light glows voltage applied to the circuit. rate troubleshooting.
brightly, the battery is strong enough for testing.
*A self-powered test light should not be
l Ammeter-an ammeter measures the amount
- I
used on any computer controlled system or of current flowing through a circuit in units called
component. The small amount of electricity amperes or amps. At normal operating voltage, most
circuits have a characteristic amount of amperes, OPEN CIRCUITS
transmitted by the test light is enough to
damage many electronic automotive compo- called “current draw” which can be measured using
an ammeter. By referring to a specified current draw # See Figure 8
nents.
rating, then measuring the amperes and comparing
MULTIMETERS the two values, one can determine what is happening
within the circuit to aid in diagnosis. An open circuit,
for example, will not allow any current to flow, so the
Multimeters are an extremely useful tool for trou-
bleshooting electrical problems. They can be pur- ammeter reading will be zero. A damaged component
or circuit will have an increased current draw, so the
chased in either analog or digital form and have a
reading will be high. The ammeter is always con-
price range to suit any budget. A multimeter is a volt-
netted in series with the circuit being tested. All of
meter, ammeter and ohmmeter (along with other fea-
the current that normally flows through the circuit
tures) combined into one instrument. It is often used
must also flow through the ammeter; if there is any
when testing solid state circuits because of its high
other path for the current to follow, the ammeter read-
input impedance (usually 10 megaohms or more). A
ing will not be accurate. The ammeter itself has very
brief description of the multiieter main test functions
follows: little resistance to current flow and, therefore, will not
affect the circuit, but it will measure current draw only
l Voltmeter--the voltmeter is used to measure
when the circuit is closed and electricity is flowing.
voltage at any point in a circuit, or to measure the
Excessive current draw can blow fuses and drain the
voltage drop across any part of a circuit. Voltmeters
battery, while a reduced current draw can cause mo-
usually have various scales and a selector switch to
tors to run slowly, lights to dim and other compo-
allow the reading of different voltage ranges. The
nents to not operate properly.

.
6-6 CHASSIS ELECTRICAL
This test already assumes the existence of an open
in the circuit and it is used to help locate the open
portion
1. Isolate the circuit from power and ground.
2. Connect the self-powered test light or ohmme-
ter ground clip to the ground side of the circuit and
probe sections of the circuit sequentially.
3. If the light is out or there is infinite resistance,
the open is between the probe and the circuit ground.
4. If the light is on or the meter shows continuity,
the open is between the probe and the end of the cir-
cuit toward the power source.
SHORT CIRCUITS
*Never use a self-powered test tight to per-
form checks for opens or shorts when power Fig. 10 Checking the resistance of a coolant
temperature sensor with an ohmmeter.
Reading is 1.04 kilohms
is applied to the circuit under test. The test
linht man he dmn~nsrl hu nutnitls nnuva~ if there is more than one load in the circuit, since all m.3.m. “Y.. “1 “ulll”y”” u, ““..7IYG p”“lz’.
1. Isolate the circuit from power and ground.
2. Connect the self-powered ’ .,.*. ,
ted ugnt or onmme-
ter ground clip to a good ground
and probe any easy-
to-reach point in the circuit.
3. If the light comes on or there is continuity,
there is a short somewhere in the circuit.
4. To isolate the short, probe a test point at either
end of the isolated circuit (the light should be on or
the meter should indicate continuity).
5. Leave the test light probe engaged and se- voltage drops are cumulative.
1. Set the voltmeter selector switch to the 20 volt
^,.^X^..
pJbl1IUII.
2. Connect the multimeter negative lead to a
good ground.
3. Operate the circuit and check the voltage prior
.
to the hrst component (load).
4. There should be little or no voltage drop in the
circuit prior to the first component. If a voltage drop
exists, the wire or connectors in the circuit are sus-
WY.+
)JGW 5. While operating the first component in the cir-
.
positive meter lead and observe the voltage readings.
A small voltage drop should be noticed. This voltage
drop is caused by the resistance of the component.
6. Repeat the test for each component (load)
de .-IL- .‘.. .I
uuwn me crrcun. quentially open connectors or switches, remove
parts, etc. until the light goes out or continuity is bro-
ken
6. When the light goes out, the short is between
the last two circuit components which were opened,
nl -r*l?I-
VuLlHbt
This test determines voltage available from the
battery and should be the first step in any electrical
troubleshooting procedure after visual inspection,
Many electrical problems, esoeciallv on comouter
controlled systems, can be caused by a low state of 7. If a large voltage drop is noticed, the preceding
component, wire or connector is suspect.
# See Figures
10 and 11
charge in the battery. Excessive corrosion at the bat-
tery cable terminals can cause poor contact that will
prevent proper charging and full battery current flow,
1. Set the voltmeter selector switch to the 20V
position.
2. Connect the multimeter negative lead to the
h*+tnn,‘n nnn,,,;~,,. , ..^,a ^-L.--:^^l --_I ‘I- ---!I?... Never use an ohmmeter with power applied
to the circuit. The ohmmeter is designed to
operate on its 0 wn power supply. The normal
1^
. . . . . Fig. 11 Spark plug wires can be checke;
MW~ 3 IlG~dllYt: t-1 pUSI UI Lellllllldl allU lilt, pUSlIlVe lead to the battery’s positive (t) post or terminal.
3. Turn the ignition switch ON to provide a load,
4. A well charged battery should register over 12
volts. If the meter reads below 11 5 vnlts tha hq*anr
_ _ .-, . power may be insufficient to operate the eler ii! volt electrical system voltage could dam-
age the meter!
1. Isolate the circuit from the vehicle’s power
CnlOrAn I)““IW. 2. Ensure that the ignition key is OFF when dis- Almost anyone can replace damaged wires, as
long as the proper tools and parts are available. Wire
and terminals are available to fit almost any need.
Even the specialized weatherproof, molded and hard
shell connectors are now cl mdicm available from aftermarket
system properly.
connecting any components or the battery. ““yp,8w’“.
3. Where necessary, also isolate at least one side Be sure the ends of all the wires are fitted with the
VOLTAGEDROP of the circuit to be checked, in order to avoid reading proper terminal hardware and connectors. Wrapping
parallel resistances. Parallel circuit resistances will a wire around a stud is never a permanent solution
# See Figure 9 always give a lower reading than the actual resistance and will only cause trouble later. Replace wires one at
When current flows through a load, the voltage be- of eifhy n< +hn hmnnh-r
GI “I II It: “I a lb1 It?>. a time to avoid confusion. Always route wires exactly
4.
Connect the meter leads to both sides of the the same as the factory.
yond the load drops. This voltage drop is due to the
resistance created by the load and also by small re- circuit (wire or component) and read the actual mea-
sured ohms on the meter scale. Make sure the selec- *If connector repair is necessary, only at-
sistances created by corrosion at the connectors and
tor switch is set to the proper ohm scale for the cir- tempt it if you have the proper tools. Weath-
damaged insulation on the wires. The maximum al- erproof and hard shell connectors require
lowable voltage drop under load is critical, especially cuit being tested, to avoid misreading the ohmmeter
test value. spectal tools to release the pins inside the
connector. Attempting to repair these con-
nectors with conventional hand tools will
damage them.