check engine ISUZU TROOPER 1995 Workshop Manual

6E2-80 DRIVEABILITV AND EMISSIONS
Circuit Description:
DIAGNOSTIC TROUBLE CODE (DTC) 42
IGNITION CONTROL (IC) CIRCUIT
The Electronic Ignition (EI) module sends a reference signal (YEL/RED wire) to the Engine Control Module (ECM),
when the engine is cranking. While the engine speed is under 500 revolution per minute, the ignition control (IC)
module will control ignition timing. When the engine speed exceeds 500 revolution per minute, the ECM applies 5
volts to the bypass line to switch the timing to ECM control.
When the system is running on the El module, that is, no voltage on the bypass line, the El module grounds the IC
signal. The ECM expects to sense or detect no voltage on the IC line during this condition. If it senses or detects a
voltage,
it sets Diagnostic Trouble Code (DTC) 42 and will not go into the IC mode.
When the revolution per minute
for IC is reached (about 500 revolution per minute), voltage will be applied to the
bypass
line. The IC should no longer be grounded in the El module, so the IC voltage should be varying.
If the bypass line is open or grounded, the El module will not switch to IC mode, so the IC voltage will be low and
DTC 42 will be set.
If the IC line is grounded, the El module will switch to IC but, because the line is grounded, there will be no IC signal.
A DTC 42 will be set.
Test Description: Number(s) below refer to circled
number(s) on the diagnostic chart.
CD DTC 42 means the ECM has detected an open or
short to ground in the IC or bypass circuits. This
test confirms
DTC 42 and that the fault causing the
DTC is present.
® Checks for a normaiiC ground path through the IC
module. An IC circuit wire, shorted to ground, will
also
read less than 500 ohms, however, this will
be checked later.
® As the test light voltage touches bypass circuit
wire, the
module should switch, causing the ohmmeter
to "over-range" if the
meter is in the
1000-2000 ohms position. Selecting the 10-20,000
ohms position will indicate above 5000 ohms. The
important thing is that the module
"switched."
® The module did not switch and this step checks
for:
• IC circuit wire shorted to ground.
• Bypass circuit wire open.
• Faulty IC module connection or module.
@ Confirms that DTC 42 is a faulty ECM and not an
intermittent in circuit wire or bypass circuit wire.
ENGINE CONTROL
MODULE(ECM)
~--------------------------VEL
~----------------------YE~RED
~----------------------YE~BLU
IC SIGNAL
REF HIGH
REF LOW
BY PASS YE~GRN D11
BLK/ORN ----)}-BLK!YEL ~ TO IGN
BLK/RED -TO TACHOMETER SWITCH
BLK ~ AND TCM (C91-D12)
WHT :' '1 CRANKSHAFT
BLK -----..~ ! POSITION
WHT/RED ',_; 1 SENSOR
"SHIELD
Fig. 6E2-45
..

6E2-82 DRIVEABILITY AND EMISSIONS
Circuit Description:
DIAGNOSTIC TROUBLE CODE (DTC) 43
KNOCK SENSOR (KS) CIRCUIT
(DOHC)
Knock Sensor (KS) is accomplished with a module that sends a voltage signal to the Engine Control Module (ECM).
As the KS detects engine knock, the voltage from the KS module to the ECM drops, and this signals the ECM to
retard timing. The ECM will retard the timing when knock is detected and revolution per minute is above about 880
revolution
per minute.
Diagnostic
Trouble Code (DTC) 43 means the ECM has been low voltage at CKT 010 for longer than 4.0 seconds
with the engine running or the system has
failed the functional check.
DTC 43 will set when:
• After run spark, more than 4 seconds
• KS input signal has been low more than 4 seconds
Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.
CD If the conditions for a DTC 43 are present the "Scan tool" will always display "YES". There should not be a
knock at
idle unless an internal engine problem, or a system problem exists.
® This test will determine if the system is functioning at this time. Usually a KS signal can be generated by
tapping on the right exhaust
manifold. If no KS signal is generated try tapping on block close to the area of the
sensor.
® Because DTC 43 sets when the signal voltage on CKT 010 remains low this test should cause the signal on
CKT to go high. The 12 volts signal should be seen by the ECM as "no knock" if the ECM and wiring are OK.
@ This test will determine if the KS signal is being detected on CKT WHT or if the KS module is at faulty.
@ If CKT WHT is routed is close to secondary ignition wires the KS module may see the interference as a KS
signal. ~
® This checks the ground circuitto the module. An open ground will cause the voltage on CKT 010 to be about 5
volts which would cause the DTC 43 functional test to fail.
(J) Contacting CKT WHT with a test light to 5 volts should generate a KS signal. This will determine if the KS
module is operating correctly.
Diagnostic Aids: DTC43 can be caused by a faulty connection atthe KS module or atthe ECM. Also check CKT
010 for possible open or short to ground.
Refer
to "lntermittents" in "Symptoms," Section "6E2-B".
TWO-WAY CONNECTOR
BLACK AT REAR OF INTAKE
-' / I I
WHT
BLK!YEL
LOCATED REAR OF 0 INTAKE PLENUM
1-----L T GRN/YEL
KNOCK
SENSOR
MODULE
BLK/YEL
GROUND
TOECM ~ TERMINAL ENGINE A12 GROUND
0 LOCATEDAT _ DRIVER'S SIDE REAR OF CYLINDER HEAD
Fig. 6E2-46
RED/GRN
+ TO MAIN RELAY
ENGINE CONTROL MODULE(ECM)
KNOCK SENSOR SIGNAL INPUT

CD
DRIVEABILITV AND EMISSIONS 6E2-83
• ENGINE IDLING.
DIAGNOSTIC TROUBLE CODE (DTC) 43
KNOCK SENSOR (KS) CIRCUIT
(DOHC)
• "SCAN TOOL" SET ON KNOCK SENSOR (KS} SIGNAL. IS THERE A KS SIGNAL INDICATED?
~ $
• DISCONNECT KS MODULE. ® • ENGINE IDLING.
• ENGINE IDLING. • TAP ENGINE BLOCK IN AREA OF KS. • PROBE HARNESS TERMINAL "C" (CKT • IS A KS SIGNAL INDICATED WHILE TAPPING ON
D10} WITH A TEST LIGHT CONNECTED
ENGINE?
TO 12 VOLTS. AFTER SECONDS, DOES "SCAN TOOL"
DISPLAY A KS SIGNAL?
$ ~ ~ ~ • IGNITION "ON". CKT D10 OPEN, @ • DISCONNECT KS MODULE. DIAGNOSTIC
TROUBLE
• PROBE TERMINAL SHORTED TO • PROBE HARNESS TERMINAL "D" CODE 43 IS INTERMITTENT. "D" WITH A TEST
GROUND, OR WITH A TEST LIGHT TO 12V. IF NO ADDITIONAL
LIGHT TO GROUND. FAULTY ENGINE DIAGNOSTIC TROUBLE
CONTROL CODES WERE STORED,
MODULE.
REFER TO "DIA~= AIDS" ON FAGIN .
I I
LIGHT "ON" I LIGHT "OFF" I LIGHT "ON" j LIGHT "OFF" I
I
I
• REMOVE TERMINAL TERMINAL "D" (J) • RECONNECT KS MODULE. REPAIR
OPEN GROUND I "E" FROM
OPEN, • DISCONNECT KS . CONNECTOR.
SHORTED TO • ENGINE IDLING.
• RECONNECT KS GROUND. • MOMENTARILY TOUCH KS MODULE.
HARNESS IS TERMINAL "E" • ENGINE IDLING. WITH A TEST LIGHT TO 12V. IS THERE A KS • EACH TIME THE TEST LIGHT
SIGNAL INDICATED?
CONTACTS TERMINAL "E", A KS SIGNAL SHOULD BE GENERATED. • IS A KS SIGNAL
INDICATED WITH "SCAN TOOL"?
~ $
~
FAULTY CONNECTION AT SENSOR TERMINAL "E" OPEN. OR FAULTY KS. SHORTED
TO GROUND,
~
FAULTY CONNECTION AT KS MODULE, OR FAULTY KS MODULE. FAULTY @ • IF AN AUDIBLE KNOCK CAN BE HEARD, CONNECTION
REPAIR INTERNAL ENGINE PROBLEM. IF OK, OR CHECK FOR ROUTING OF WIRE FROM KS TO KS MODULE. KS MODULE FOR PICKING UP FALSE KS SIGNALS FROM AN ADJACENT WIRE.
REROUTE AS NECESSARY. IF ROUTING IS CORRECT, REPLACE KS.

6E2-84 DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) 44
HEATED OXYGEN SENSOR (H02S) CIRCUIT
(LEAN HEATED OXYGEN SENSOR (H02S) SIGNAL INDICATED)
Circuit Description:
The engine control module supplies a voltage of about .43 volt between terminals "83" and "82". (If measured
with a
10 megohm digital voltmeter, this may read as low as .32 volts.) The Heated Oxygen Sensor (H02S) varies
the
voltage within a range of about 1 volt, if the exhaust is rich, down through about .1 0 volt, if exhaust is lean.
The sensor is like an open circuit and produces no voltage, when it is below about 360°C (600°F). An open sensor
circuit,
or cold sensor, cause "Open Loop" operation.
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
CD Diagnostic Trouble Code (DTC) 44 is set, when the 02S signal voltage is fixed below .1 00 mV and the
following:
• Throttle
position sensor greater than 9.8%.
• No DTC 21 or 33. • Oxygen signal voltage is steady between .347
volt and .547 volt.
•
The engine has been running at least for 180 •
seconds. • • System is operating in "Closed Loop". •
Engine Operation Temperature 69SC (155°F).
All of the above conditions present for 25 sec .
Integrator not at 128 .
Diagnostic Aids:
Using the "Scan tool", observe the block learn value at different revolution per minute. The "Scan tool" also
displays
the block cells, so the block learn values can be checked in each ofthe cells, to determine when the DTC 44
may have been set.
If the conditions for DTC 44 exist, the block learn values will be around 150.
•
Check for ground in wire between connector sensor.
• Fuel Contamination-Water, even in small amounts, near the in-tank fuel pump inlet can be delivered to the
injector. The water causes a
lean H02S signal and can set a DTC 44.
• Fuel Pressure-System will be lean if pressure is too low. If may be necessary to monitor fuel pressure,
while driving the car at various road speeds and/or loads to confirm. See Fuel System diagnosis CHART A-5.
• Exhaust Leaks -lfthere is an exhaust leak, the engine can cause outside air to be pulled into the exhaust and
past the sensor.
Vacuum or crankcase leaks can cause a lean condition.
• If DTC 44 is intermittent, refer to Section "6E2-8".
• Fuel
Injectors-The wrong fuel injector(s) could be the cause of a lean H02S signal condition. Verify that the
correct
fuel injector(s) are installed in the vehicle. Refer to the service parts manual for correct part and part
number.
Refer
to "Engine Control Module and Sensors", Section "6E2-C1" for proper diagnosis.
TRANSMISSION
HARNESS
CONNECTOR
~BLK1
TRANSMISSION
HARNESS CONNECTOR
(BLUE) I /' BL~GRN~r-~----------~-------BLU
RED/BLU (MfT) --(( 1
1 ; « RED
(BLUE) ~
PASSENGER Q SIDE
LT BLU (A/T) L
WHT/RED 1
P:::l=t=t1 l BL~GRN ----.-----BL~GRN
BLK!YEL BL~BLU FENDER 02 --·S HEATER ELEMENT l
ENGINE
DRIVER'S SIDE BLOCK REAR AT CYLINDER
TRANSMISSION HARNESS _ HEAD CONNECTOR (BLUE)
10A -----BL~GRN ____ .,.... ~3EL PUMP RELAY
Fig. 6E2-47
ENGINE CONTROL
MODULE(ECM)
H02SGROUND REFERENCE
H02SSIGNAL
ECM GROUNDS
ECM GROUNDS
..

DRIVEABILITY AND EMISSIONS 6E2-85
DIAGNOSTIC TROUBLE CODE (DTC) 44
HEATED OXYGEN SENSOR (H02S) CIRCUIT
(LEAN HEATED OXYGEN SENSOR (H02S) SIGNAL INDICATED)
(j) •
RUN WARM ENGINE (69SC/155'F) AT 1200 REVOLUTIOM PER MINUTE
• DOES "SCAN TOOL" INDICATE OXYGEN (02) VOLTAGE FIXED BELOW 0.10 VOLTS (100 mV)
• DISCONNECT HEATED OXYGEN SENSOR (H02S).
• WITH ENGINE IDLING, "SCAN TOOL" SHOULD DISPLAY
H02S BETWEEN .35 VOLTS AND .55 VOLTS (350 mV AND 550 mV). DOES IT?
DIAGNOSTIC TROUBLE CODE 44 IS INTERMITTENT. IF NO ADDITIONAL DIAGNOSTIC TROUBLE CODES WERE STORED, REFER TO "DIAGNOSTIC AIDS" ON FACING I?,Aer.
H02S SIGNAL CKT SHORTED TO GROUND OR FAULTY ENGINE CONTROL MODULE
CLEAR DIAGNOSTIC TROUBLE CODES AND CONFIRM "CLOSED LOOP" OPERATION AND NORMAL "CHECK ENGINE" MALFUNCTION
INDICATOR LAMP OPERATION.

6E2-86 DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) 45
HEATED OXYGEN SENSOR (H02S) CIRCUIT
(RICH
HEATED OXYGEN SENSOR (H02S) SIGNAL INDICATED)
Circuit Description:
The Engine Control Module (ECM) supplies a voltage of about .45 volt between terminals "83" and "82". (If
measured with a 10 megohm digital voltmeter, this may read as low as .32 volts.) The Heated Oxygen Sensor
(H02S)
varies the voltage within a range of about 1 volt, if the exhaust is rich, down through about .1 0 volt, if
exhaust is lean.
The sensor is like an open circuit and produces no voltage, when it is below about 360"C (600"F). An open sensor
circuit,
or cold sensor, cause "Open Loop" operation.
Test Description:
Numbers below refer to circled numbers ·on the diagnostic chart.
CD Diagnostic Trouble Code (DTC) 45 is set, when the H02S signal voltage is fixed above .1 0 volts (1 00 mV) under
the
following conditions:
• Throttle position sensor greater than 9.8%. • 02 Signal Voltage is les than 0.347 volts and
• No DTC 21 A/21 8 or 33A/338. greater than .547 volts.
•
The engine is running for longer than 180 • Temperature above 69.5"C (155"F).
seconds. • Integrator not at 128
• System is operating in "Closed Loop". • All of the above condition present for 50 sec.
Diagnostic Aids:
The DTC 45, or rich H02S signal, is most likely caused by one of the following:
• Fuel Pressure-System will go rich, if pressure is too high. The ECM can compensate for some increase.
However,
if it gets too high, a DTC 45 will be set. See Fuel System diagnosis CHART A-5.
• HEI Shielding-An open ground CKT BLK/GRN may result in EMI, or induced electrical "noise". The ECM
looks at this "noise" as reference pulses. The additional pulses result in a higher than actual engine speed
signal. The ECM then delivers too much fuel, causing system to go rich. Engine tachometer will also, show ~
higher than actual engine speed, which can help in diagnosing this problem.
• Evaporate emission canister purge-Check for fuel saturation. If full of fuel, check canister control and
hoses.
See evaporate emission canister purge, Section "C3".
• Manifold absolute pressure (MAP) sensor-An output that causes the ECM to sense a higher than normal
MAP (low vacuum) can causethesystemto go rich. Disconnecting the MAP sensor will allow the ECMtoseta
fixed value for the MAP sensor. Substitute a different MAP sensor, if the rich condition is gone, while the
sensor is disconnected.
• Throttle position sensor-An intermittent throttle position sensor output will cause the system to go rich,
due
to a false indication of the engine accelerating.
• 02 sensor contamination -Inspect H02S for silicone contamination from fuel, or use of improper RTV
sealant. The sensor may have a white, powdery coating and result in a high, but false signal voltage (rich
H02S signal indication). The ECM will then reduce the amount of fuel delivered to the engine, causing a
severe surge driveability problem.
• Exhaust gas recirculation -Valve sticking open at idle, usually accompanied by a rough idle, or stall
complaint, especially at idle. Refer to CHART C-7A to check exhaust gas recirculation system.
If DTC 45 is intermittent, refer to Section "6E2-8".
TRANSMISSION
HARNESS
CONNECTOR ,[BLK1
TRANSMISSION
HARNESS CONNECTOR !BLUE I I ,, BLK!GRN~E----r:......,-----"*----BLU
RED/BLU (MfT) ~ 1
1 1 RED
(BLUE) ~
PASSENGER Q SIDE FENDER
L T
BLU (AfT) L WHT/RED 1
R=+=+=:R l BLK!GRN -----BLK!GRN
BLK/YEL BLK!BLU
1
ENGINE
BLOCK Q TRANSMISSION HARNESS -CONNECTOR (BLUE) -
DRIVER'S SIDE REAR AT CYLINDER HEAD
10A BLK/GRN -~~EL PUMP RELAY
Fig. 6E2-48
ENGINE CONTROL MODULE(ECM)
02SGROUND REFERENCE 02S SIGNAL
ECM GROUNDS
ECM GROUNDS
..

DRIVEABILITY AND EMISSIONS 6E2-87
DIAGNOSTIC TROUBLE CODE (DTC) 45
HEATED OXYGEN SENSOR (H02S) CIRCUIT
(RICH
HEATED OXYGEN SENSOR (H02S) SIGNAL INDICATED)
Q) • RUN WARM ENGINE (69.5"C/155"F) AT 1200 REVOLUTION PER MINUTE
• DOES "SCAN TOOL" DISPLAY HEATED OXYGEN SENSOR VOLTAGE FIXED ABOVE .75 VOLTS (750 mV)?
• DISCONNECT HEATED OXYGEN SENSOR AND JUMPER HARNESS CKT SYBLU TO GROUND.
• "SCAN TOOL" SHOULD DISPLAY OXYGEN BELOW
.35 VOLTS (350 mV). DOES IT?
DIAGNOSTIC TROUBLE CODE 45 IS INTERMITTENT. IF NO ADDITIONAL DIAGNOSTIC TROUBLE CODES WERE STORED, REFER TO "DIAGNOSTIC AIDS" ON FACING P
CLEAR
DIAGNOSTIC TROUBLE CODES AND CONFIRM "CLOSED LOOP" OPERATION AND NORMAL "CHECK ENGINE" MALFUNCTION
INDICATOR LAMP OPERATION.

6E2-88 DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) 51
ENGINE CONTROL MODULE (ECM) FAILURE ECM FAILED OR
ELECTRICALLY
ERASABLE PROGRAMMABLE READ ONLY MEMORY FAILURE)
CHECK THAT ALL ECM CONNECTIONS ARE GOOD
IF OK, CLEAR MEMORY AND RECHECK ECM.
IF CODE 51 REAPPEARS, REPLACE ECM.
CLEAR DIAGNOSTIC TROUBLE CODES AND CONFIRM "CLOSED LOOP" OPERATION AND NORMAL "CHECK ENGINE" MALFUNCTION
INDICATOR LAMP OPERATION.
Ill

DRIVEABILITY AND EMISSIONS 6E2-89
SECTION B
SYMPTOMS
CONTENTS
Important Preliminary Checks . . . . . . . . . 6E2-89
Before Starting . . . . . . . . . . . . . . . . . . . . . . 6E2-89
Symptom . . . . . . . . . . . . . . . . . . . . . . . . . . . 6E2-89
Visual/Physical Check . . . . . . . . . . . . . . . . 6E2-89
lntermittents . . . . . . . . . . . . . . . . . . . . . . . . 6E2-90
Hard Start . . . . . . . . . . . . . . . . . . . . . . . . . . 6E2-90
Surges and/or Chuggles .............. 6E2-91
Lack of Power, Sluggish, or Spongy . . . . 6E2-92
Detonation/Spark Knock .............. 6E2-92
Hesitation, Sag, Stumble . . . . . . . . . . . . . 6E2-93
Cuts Out, Misses . . . . . . . . . . . . . . . . . . . . . 6E2-93
Rough, Unstable, or Incorrect Idle,
Stalling ............................. 6E2-94
Poor Fuel Economy . . . . . . . . . . . . . . . . . . . 6E2-95
Excessive Exhaust Emissions or Odors .. 6E2-96
Backfire . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6E2-96
Dieseling, Run-on .................... 6E2-97
Restricted Exhaust System
Check (CHART B-1) ................... 6E2-98
IMPORTANT PRELIMINARY CHECKS
BEFORE STARTING
Before using this section you should have performed
the on-board diagnostic system check and determined
that:
1. The engine control module and "Check Engine"
malfunction indicator lamp are operating
correctly.
2. There are no diagnostic trouble codes stored, or
there is a diagnostic trouble code but no "Check
Engine" malfunction indicator lamp.
SYMPTOM
Verify the customer complaint, and locate the correct
symptom in the
table of contents. Check the items
indicated under
that symptom.
VISUAL/PHYSICAL CHECK
Several of the symptom procedures call for a Careful
Visual/Physical
Check. The importance of this step
cannot
be stressed too strongly -it can lead to
correcting a
problem witho'ut further checks and can
save
valuable time. This check should include: •
Engine control
module grounds for being clean,
tight and in their proper location.
•
Vacuum hoses for splits, kinks, and proper
connections,
as shown on "Vehicle Emission
Control Information" label. Check thoroughly for
any type of leak or restriction.
• Air leaks atthrottle body mounting area and intake
manifold
sealing surfaces.
• Ignition wires for cracking, hardness, proper
routing and carbon tracking.
• Wiring for proper connections, pinches and cuts.
• Fuel lines for being pinched or misrouted.

6E2-90 DRIVEABILITY AND EMISSIONS
INTERMITTENTS
Definition: Problem may or may not turn "ON" the
"Check Engine" malfunction indicator lamp or store
Diagnostic
Trouble Code (DTC).
DO NOT use the DTC charts in "Engine Components/
Wiring Diagrams/Diagnostic
Charts," Section "6E2-A"
for intermittent problem. The fault must be present to
locate the problem. If a fault is intermittent, use of DTC
charts may result in replacement of good parts.
•
• Most intermittent problems are caused by faulty
electrical
connections or wiring. Perform careful
visual/physical
check as described at start of
"Symptoms," Section "6E2-B." Check for:
Poor mating
of the connector halves. or
terminal not fully seated in the connector body
(backed out).
Improperly formed or damaged terminal. All
connector
terminals in the problem circuit
should be carefully reformed or replaced to
insure proper contact tension.
Poor
terminal to wire connection. This
requires removing the
terminal from the
connector body to check. Refer to
SECTION 8
"Wiring Harness Service,"
If a visual/physical check does not find the cause
of the problem, the car can be driven with a
voltmeter connected to a suspected circuit. A
"Scan tool" can also be used to help detect
intermittent conditions. An abnormal
voltage, or
"Scan" tool reading, when the problem occurs,
indicates the
problem may be in that circuit. If the wiring
and connectors check
OK, and a DTC was
stored
for a circuit having a sensor, except for
DTC(s) 44 and 45, substitute a known good sensor
and recheck.
• Loss of DTC memory. To check, disconnect
throttle position (TP) sensor and idle engine until
"Check
Engine" malfunction indicator lamp comes
"ON". DTC 21 should be stored, and kept in
memory when ignition is turned "OFF". If not, the
Engine
Control Module (ECM) is faulty.
•
An intermittent "Check Engine" malfunction
indicator
lamp with no stored DTC may be caused
by:
Ignition coil shorted to ground and arcing at
spark
plug wires or plugs.
"Check
Engine" malfunction indicator lamp
wire to ECM shorted to ground.
Diagnostic
"test" terminal wire to ECM,
shorted to ground.
ECM grounds, refer to ECM wiring diagrams.
• Check for an electrical system interference caused
by a defective
relay, ECM driven solenoid, or
switch. They can cause a sharp electrical surge.
Normally, the problem will occur when the faulty
component is operated.
• Check for improper installation of electrical
options such as lights, 2 way radios, etc.
• Ignition control wires should be routed away from
spark plug wires, electronic ignition (EI) wires, El
housing, coil and generator. Ground wire from
ECM to El should have a good connection.
• If problem has not been found, refer to "ECM
Connector Symptom" charts at the end of
"Symptoms," Section "6E2-B."
HARD START
Definition: Engine cranks OK, but does not start for a
long time. Does eventually run, or may
start
but immediately dies.
PRELIMINARY CHECKS
• Perform the careful visual/physical checks as
described at start of "Symptoms," Section "6E2-
B".
•
Make sure the driver is using the correct starting
procedure.
SENSORS
• CHECK: Engine coolant temperature sensor using
a
"Scan tool", compare engine coolant
temperature with ambient temperature
on
cold engine. -
If engine coolant temperature
readings
is 5 degrees greater than or less than
ambient air temperature on a
cold
engine, check resistance in engine
coolant temperature sensor circuit
or
sensor itself. Compare engine coolant
temperature sensor resistance value
to the "Diagnostic Aids" chart on
DTC
14 chart.
• CHECK: Manifold absolute pressure sensor.
Check for flooding and/or correct sensor
for vehicle.
• CHECK: TP sensor for binding or a high TP sensor
voltage with the throttle closed (should
read between 0.54 volt and 1.25 volts.)