ignition MERCEDES-BENZ SPRINTER 2006 Service Manual

BODY VERIFICATION TEST - VER 1 APPLICABILITY
1. Disconnect all jumper wires and reconnect all previously disconnected components and
connectors.
2. Ensure that all accessories are turned off and the battery is fully charged.
3. NOTE: Refer to the service information for proper programming procedures if the
ABM; ACM; ATC; CTM; ECM; IC; SKREEM; SLA; or SSM was replaced.
4. If the SKREEM was replaced, program all RKE transmitters used with this vehicle.
5. NOTE: Perform the next 8 steps of this procedure if either diagnosing the
Automatic Temperature Control (ATC) system or if repairs were made to the ATC
system. All of the following criteria must be met in order to successfully run the ATC
Function Test.
6. With DRBIIIt, record and erase ATC DTCs.
7. Place the shift lever in Park.
8. Start the engine. Allow the engine to reach normal operating temperature.
9. Set the blower to high speed.
10. Press the Air Conditioning switch On.
11. With the DRBIIIt, verify that the ambient temperature is above 59ÉF (15ÉC), the refrigerant
pressure is between 29 and 348 PSI (2 and 24 bar), the evaporator temperature is above 36.5ÉF
(2.5ÉC), and the coolant temperature is above 158ÉF (70ÉC).
12. With the DRBIIItin ATC, select System Tests and select ATC Function Test. When the ATC
Function Test is complete, proceed to the next step of this procedure.
13. With the DRBIIIt, read active ATC DTCs. If any DTC is active or if the original condition
is still present, proceed to the conclusion question and answer Yes.
14. With the DRBIIIt, record and erase all DTCs from ALL modules. Start and run the engine
for 2 minutes. Operate all functions of the system that caused the original concern.
15. Turn the ignition off and wait 5 seconds. Turn the ignition on and using the DRBIIIt, read
DTCs from ALL modules.
Are any DTC's present or is the original condition still present?All
Ye s!Repair is not complete, refer to the appropriate symptom.
No!Repair is complete.
80
VERIFICATION TESTS
Verification Tests ÐContinued

9.0 CONNECTOR PINOUTS
BRAKE FLUID LEVEL SWITCHCAV CIRCUIT FUNCTION
1 20BR/YL BRAKE FLUID LEVEL INDICATOR SIGNAL
2 16BR GROUND
BRAKE LAMP SWITCH C1 (EXCEPT ESP)CAV CIRCUIT FUNCTION
1 20WT BRAKE SWITCH OUTPUT
2 16RD/BK FUSED IGNITION SWITCH OUTPUT (RUN-START)
3 20BK/BL/RD BRAKE LAMP SWITCH
4- -
BRAKE LAMP SWITCH C2 (EXCEPT ESP) - BLACKCAV CIRCUIT FUNCTION
1 16BK/BL/WT FUSED IGNITION SWITCH OUTPUT (RUN-START)
2 16BK/RD BRAKE LAMP SWITCH OUTPUT
3- -
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CONNECTOR PINOUTS

INSTRUMENT CLUSTER C2 - WHITECAV CIRCUIT FUNCTION
1- -
2- -
3 20RD/YL FUSED B(+)
4 20BR/WT BRAKE WEAR SENSOR SIGNAL
5- -
6 18BR GROUND
7 20GY/DG/RD LAMP DRIVER
8 20BL/WT FUSED HIGH BEAM SWITCH OUTPUT
9 20BL/RD/WT VEHICLE SPEED SENSOR OUTPUT
10 20BK FUSED IGNITION SWITCH OUTPUT (RUN-START)
11 20BL/BK KEY-IN IGNITION SWITCH SIGNAL
12 - -
13 20BK/WT LEFT TURN SIGNAL
14 20BR/YL BRAKE FLUID LEVEL INDICATOR SIGNAL
15 20BL GENERATOR FIELD DRIVER
16 20YL AIRBAG WARNING INDICATOR DRIVER
17 - -
18 20BL/VT D(+) RELAY NO. 1 CONTROL
18 20BL/VT D(+) RELAY NO. 1 CONTROL
STEERING ANGLE SENSORCAV CIRCUIT FUNCTION
1 20DG/WT CAN C BUS (-)
2- -
3 20DG CAN C BUS (+)
4- -
5 20BK/RD FUSED OPTIONAL EQUIPMENT RELAY OUTPUT
6 20BR GROUND
TCS SWITCH (ASR) - BLACKCAV CIRCUIT FUNCTION
1 16GY/DG/RD LAMP DRIVER
2- -
3 18BK/BL TCS SWITCH (ASR) SENSE
4- -
5- -
6- -
7 16BK/BL/DG FUSED IGNITION SWITCH OUTPUT
8- -
9- -
10 16BR GROUND
WHEEL SPEED SENSOR-LEFT FRONTCAV CIRCUIT FUNCTION
1 18BK LEFT FRONT WHEEL SPEED SENSOR (+)
2 18BR LEFT FRONT WHEEL SPEED SENSOR (-)
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CONNECTOR PINOUTS

TABLE OF CONTENTS - Continued
P1480-GLOW PLUG INDICATOR ERROR...................................79
P1482-GLOW PLUG MODULE - COMMUNICATION ERROR....................80
P2537-GLOW PLUG CONTROL CIRCUIT PREGLOW FAULT...................80
P2537-GLOW PLUG CONTROL CIRCUIT PREGLOW SHORT TO GROUND.......80
P2537-GLOW PLUG CONTROL CIRCUIT PREGLOW SHORT TO VOLTAGE......80
P1482-GLOW PLUG MODULE - EXCESS CURRENT..........................82
P2133-GLOW PLUG #1 CIRCUIT EXCESSIVE CURRENT......................82
P2133-GLOW PLUG #1 CIRCUIT OPEN CIRCUIT............................82
P2133-GLOW PLUG #1 CIRCUIT SHORT TO GROUND.......................82
P2133-GLOW PLUG #1 CIRCUIT SHORT TO VOLTAGE.......................82
P2134-GLOW PLUG #2 CIRCUIT EXCESSIVE CURRENT......................82
P2134-GLOW PLUG #2 CIRCUIT OPEN CIRCUIT............................82
P2134-GLOW PLUG #2 CIRCUIT SHORT TO GROUND.......................82
P2134-GLOW PLUG #2 CIRCUIT SHORT TO VOLTAGE.......................82
P2135-GLOW PLUG #3 CIRCUIT EXCESSIVE CURRENT......................82
P2135-GLOW PLUG #3 CIRCUIT OPEN CIRCUIT............................82
P2135-GLOW PLUG #3 CIRCUIT SHORT TO GROUND.......................82
P2135-GLOW PLUG #3 CIRCUIT SHORT TO VOLTAGE.......................82
P2136-GLOW PLUG #4 CIRCUIT EXCESSIVE CURRENT......................82
P2136-GLOW PLUG #4 CIRCUIT OPEN CIRCUIT............................82
P2136-GLOW PLUG #4 CIRCUIT SHORT TO GROUND.......................82
P2136-GLOW PLUG #4 CIRCUIT SHORT TO VOLTAGE.......................82
P2137-GLOW PLUG #5 CIRCUIT EXCESSIVE CURRENT......................82
P2137-GLOW PLUG #5 CIRCUIT OPEN CIRCUIT............................82
P2137-GLOW PLUG #5 CIRCUIT SHORT TO GROUND.......................82
P2137-GLOW PLUG #5 CIRCUIT SHORT TO VOLTAGE.......................82
P1482-GLOW PLUG MODULE - INCORRECT TIMER.........................85
P1482-GLOW PLUG MODULE - INTERNAL FAULT...........................85
P2538-GLOW PLUG MODULE COMMUNICATION ERROR.....................85
P2538-GLOW PLUG MODULE EXCESSIVE CURRENT ERROR.................85
P2538-GLOW PLUG MODULE TIMER ERROR...............................85
P1610-ENGINE CONTROL RELAY PLAUSIBILITY............................87
P1610-ENGINE CONTROL RELAY SHUTS OFF TOO EARLY...................89
P1610-ENGINE CONTROL RELAY SHUTS OFF TOO LATE....................91
P1611-SENSOR SUPPLY 1 VOLTAGE IS TOO HIGH..........................94
P1611-SENSOR SUPPLY 1 VOLTAGE IS TOO LOW..........................96
P1612-IGNITION VOLTAGE - VOLTAGE ERROR.............................99
P1615-ECM VOLTAGE SUPPLY IS TOO HIGH..............................100
P1615-ECM VOLTAGE SUPPLY IS TOO LOW...............................100
P1630-IMMOBILIZER...................................................102
P1630-IMMOBILIZER...................................................102
P1630-IMMOBILIZER...................................................102
P1630-IMMOBILIZER...................................................102
P2201-IMMOBILIZER CAN MESSAGE ERROR..............................102
P2243-NO MESSAGE RECEIVED FROM SKREEM..........................102
P1681-ACM CIRCUIT FAULT.............................................104
P1681-ACM CIRCUIT SHORT TO VOLTAGE................................104
P2009-WATER IN FUEL SENSOR - WATER IN FUEL.........................106
P2009-WATER IN FUEL SENSOR SIGNAL ERROR..........................106
P2010-MASS AIR FLOW SENSOR NEGATIVE DEVIATION....................110
P2010-MASS AIR FLOW SENSOR POSITIVE DEVIATION.....................110
P2068-MASS AIR FLOW SENSOR PLAUSIBILITY SIGNAL RATIO TOO LARGE . . .110
P2068-MASS AIR FLOW SENSOR PLAUSIBILITY SIGNAL RATIO TOO SMALL . . .110
v

TABLE OF CONTENTS - Continued
KICK DOWN SWITCH - BLACK...........................................271
MASS AIR FLOW SENSOR - BLACK......................................271
OXYGEN SENSOR (OBD)...............................................271
FUSED IGNITION SWITCH RUN-START RELAY (RELAY BLOCK)..............273
SPEED CONTROL SWITCH.............................................273
WATER IN FUEL SENSOR - BLACK.......................................273
10.0 SCHEMATIC DIAGRAMS................................................275
10.1ENGINE CONTROL MODULE.......................................275
10.2ENGINE CONTROL MODULE.......................................276
11.0 CHARTS AND GRAPHS................................................277
xi

3.2.2 ECM OPERATING MODES
As input signals to the ECM change, the ECM
adjusts its response to the output devices. For
example, the ECM must calculate a different fuel
quantity and fuel timing for engine idle condition
than it would for a wide open throttle condition.
There are several different modes of operation that
determine how the ECM responds to the various
input signals.
Ignition Switch On (Engine Off)
When the ignition is turned on the ECM activates
the glow plug relay for a time period that is deter-
mined by engine coolant temperature, intake air
temperature and battery voltage.
Engine Start-Up Mode
The ECM uses the intake air temperature sensor,
engine temperature sensor and the crankshaft po-
sition sensor (engine speed) inputs to determine
fuel injection quantity.
Normal Driving Modes
Engine idle, warm-up, acceleration, deceleration
and wide open throttle modes are controlled based
on all of the sensor inputs to the ECM. The ECM
uses these sensor inputs to adjust fuel quantity and
fuel injector timing. EGR valve control is performed
using feedback from the oxygen sensor. An oxygen
sensor is located in the exhaust manifold to sample
oxygen content exiting the engine cylinders. The
ECM uses the O2 sensor, along with other sensor
inputs, to govern the amount of exhaust gas recir-
culation to reduce HC (HydroCarbons) and CO
(Carbon Monoxide). Engine coolant is routed
through the base of the EGR valve to provide
additional cooling of the exhaust gas, which further
helps the reductions of emissions. The EGR valve
has a self-cleaning function. When the engine is
shut off, the EGR valve rotates twice to reduce
carbon deposits at the valve seat.
Overheat Production Mode
If the engine temperature is above 105ÉC (221ÉF)
and vehicle speed is above 40 km/h (25 MPH) the
ECM will limit fuel quantity for engine protection.
Limp-In Mode
The ECM utilizes different degrees of engine
limp-in. The ECM is able to limit engine rpm,
engine power output (turbo boost reduction), acti-
vate engine cooling fan or all of these functions
based on the type of fault that is detected. Critical
engine performance faults such as accelerator pedal
position sensor fault will result in a fixed idle speed
of approximately 680 rpm regardless of actual pedalposition. Other less critical faults will result in
power reduction throughout the full range of driv-
ing conditions.
Overspeed Detection Mode
If the ECM detects engine RPM that exceeds
5200 RPM, the ECM will set a DTC in memory,
limit engine RPM to no more than 2500 RPM, and
illuminate the MIL until the DTC is cleared.
After-Run Mode
The ECM transfers RAM information to ROM
and performs an Input/Output state check.
3.2.3 MONITORED CIRCUITS
The ECM is able to monitor and identify most
driveability related trouble conditions. Some cir-
cuits are directly monitored through ECM feedback
circuitry. In addition, the ECM monitors the voltage
state of some circuits and compares those states
with expected values. Other systems are monitored
indirectly when the ECM conducts a rationality test
to identify problems.
Although most subsystems of the engine control
module are either directly or indirectly monitored,
there may be occasions when diagnostic trouble
codes are not immediately identified. For a trouble
code to set, a specific set of conditions must occur
and unless these conditions occur, a DTC will not
set.
3.2.4 SKREEM OVERVIEW
The sentry key remote entry module system
(SKREEM) is designed to prevent unauthorized
vehicle operation. The system consists of a sentry
key remote entry module (SKREEM), ignition
key(s) equipped with a transponder chip and the
ECM. When the ignition switch is turned on, the
SKREEM interrogates the ignition key. If the igni-
tion key is Valid or Invalid, the SKREEM sends a
message to the ECM indicating ignition key status.
Upon receiving this message the ECM will termi-
nate engine operation or allow the engine to con-
tinue to operate.
3.2.5 SKREEM ON-BOARD DIAGNOSTICS
The SKREEM has been programmed to transmit
and monitor many different coded messages as well
as CAN Bus messages. This monitoring is called
On-Board Diagnostics. Certain criteria must be met
for a DTC to be entered into SKREEM memory. The
criteria may be a range of; input voltage, CAN Bus
message or coded messages to the SKREEM. If all
the criteria for monitoring a circuit or function are
met and a fault is detected, a DTC will be stored in
the SKREEM memory and the START ERROR indi-
cator will be turned on in the instrument cluster.
2
GENERAL INFORMATION

3.2.6 SKREEM OPERATION
When ignition power is supplied to the SKREEM,
the SKREEM performs an internal self-test. After
the self-test is complete, the SKREEM energizes
the antenna (this activates the transponder chip)
and sends a challenge to the transponder chip. The
transponder chip responds to the challenge by gen-
erating an encrypted response message.
After responding to the coded message, the tran-
sponder sends a transponder ID message to the
SKREEM. The SKREEM compares the transpon-
der ID message to the available valid key codes in
SKREEM memory (8 key maximum at any one
time). After validating the ignition key the
SKREEM sends a CAN Bus message request to the
ECM, then waits for the ECM response. If the ECM
does not respond, the SKREEM will send the re-
quest again. If the ECM does not respond again, the
SKREEM will stop sending the request and store a
trouble code in memory. If the ECM sends a correct
response to the SKREEM, the SKREEM sends a
valid/invalid key message to the ECM. The ECM
will allow or disallow engine operation based on this
message.
Secret Key - an electronically stored value (iden-
tification number) that is unique to each SKREEM.
The secret key is stored in the SKREEM, ECM and
all ignition key transponders.
Challenge - a random number that is generated by
the SKREEM at each ignition key cycle.
The secret key and challenge are the two vari-
ables used in the algorithm that produces the
encrypted response message. The transponder uses
the crypto algorithm to receive, decode and respond
to the message sent by the SKREEM. After re-
sponding to the coded message, the transponder
sends a transponder ID message to the SKREEM.
3.3 DIAGNOSTIC TROUBLE CODES
Each diagnostic trouble code (DTC) is diagnosed
by following a specific procedure. The diagnostic
test procedure contains step-by-step instruction for
determining the cause of the DTC as well as no
trouble code problems. It is not necessary to per-
form all of the tests in this book to diagnose an
individual code.
Always begin diagnosis by reading the DTCs
using the DRBIIIt. This will direct you to the
specific test(s) that must be performed.
3.3.1 HARD CODE
A DTC that comes back within one cycle of the
ignition key is a hard code. This means that the
problem is current every time the ECM/SKREEM
checks that circuit or function. Procedures in this
manual verify if the DTC is a hard code at thebeginning of each test. When the fault is not a hard
code, an intermittent test must be performed.
NOTE: If the DRBIIITdisplays faults for
multiple components (i.e. ECT, MAF, IAT
sensors) identify and check the shared
circuits for possible problems before
continuing (i.e. sensor grounds or 5-volt
supply circuits). Refer to the appropriate
schematic to identify shared circuits.
3.3.2 INTERMITTENT CODE
A DTC that is not current every time the ECM/
SKREEM checks the circuit or function is an inter-
mittent code. Most intermittent DTCs are caused
by wiring or connector problems. Problems that
come and go like this are the most difficult to
diagnose; they must be looked for under specific
conditions that cause them. The following checks
may assist you in identifying a possible intermit-
tent problem.
± Visually inspect the related wire harness con-
nectors. Look for broken, bent, pushed out or
corroded terminals.
± Visually inspect the related wire harness.
Look for chafed, pierced or partially broken
wire.
± Refer to hotlines or technical service bulletins
that may apply.
NOTE: Electromagnetic (radio) interference
can cause an intermittent system
malfunction. This interference can interrupt
communication between the ignition key
transponder and the SKREEM.
3.3.3 ECM DIAGNOSTIC TROUBLE CODES
IMPORTANT NOTE: Before replacing the
ECM for a failed driver, control circuit or
ground circuit, be sure to check the related
component/circuit integrity for failures not
detected due to a double fault in the circuit.
Most ECM driver/control circuit failures are
caused by internal failures to components
(i.e. relays and solenoids) and shorted
circuits (i.e. sensor pull-ups, drivers and
ground circuits). These faults are difficult to
detect when a double fault has occurred and
only one DTC has set.
If the DRBIIItdisplays faults for multiple com-
ponents (i.e. MAF, ECT, ENG OIL, etc.), identify
and check the shared circuits for possible problems
before continuing (i.e. sensor grounds or 5-volt
3
GENERAL INFORMATION

fuel rail pressure malfunction rail pressure too high
fuel rail pressure malfunction rail pressure too low
fuel temperature sensor circuit signal voltage too
high
fuel temperature sensor circuit signal voltage too
low
fuel temperature sensor plausibility
general leakage
glow plug #1 circuit excessive current
glow plug #1 circuit open circuit
glow plug #1 circuit short to ground
glow plug #1 circuit short to voltage
glow plug #2 circuit excessive current
glow plug #2 circuit open circuit
glow plug #2 circuit short to ground
glow plug #2 circuit short to voltage
glow plug #3 circuit excessive current
glow plug #3 circuit open circuit
glow plug #3 circuit short to ground
glow plug #3 circuit short to voltage
glow plug #4 circuit excessive current
glow plug #4 circuit open circuit
glow plug #4 circuit short to ground
glow plug #4 circuit short to voltage
glow plug #5 circuit excessive current
glow plug #5 circuit open circuit
glow plug #5 circuit short to ground
glow plug #5 circuit short to voltage
glow plug control circuit preglow fault
glow plug control circuit preglow short to ground
glow plug control circuit preglow short to voltage
glow plug control module circuit open circuit
glow plug control module circuit shorted to ground
glow plug control module circuit shorted to voltage
or open
glow plug control module fault
glow plug indicator error
glow plug module communication error
glow plug module -communication error
glow plug module -excess current
glow plug module excessive current error
glow plug module -incorrect timer
glow plug module -internal fault
glow plug module timer error
ignition voltage -voltage error
immobilizer
immobilizer
immobilizer
immobilizer
immobilizer can message error
improper start attempt
injection fault excessive engine speed
injection fault -excessive temperature
injection fault -quantity error
injection fault -torque limit
injector 1 injection time above limit
injector 1 injection time below limit
injector 2 injection time above limitinjector 2 injection time below limit
injector 3 injection time above limit
injector 3 injection time below limit
injector 4 injection time above limit
injector 4 injection time below limit
injector 5 injection time above limit
injector 5 injection time below limit
injector bank error
injector bank error
injector circuit fault
injector circuit fault
injector circuit low side shorted to ground
injector circuit low side shorted to ground
injector circuit shorted to ground or voltage
injector circuit shorted to ground or voltage
instrument cluster message -ambient temperature
signal plausibility
instrument cluster message plausibility
intake air temp sensor circuit signal voltage too high
intake air temp sensor circuit signal voltage too low
intake air temp sensor signal voltage too high
intake air temp sensor signal voltage too low
intake pressure sensor can message error
intake pressure sensor circuit fault
intake pressure sensor intake restriction
intake pressure sensor open circuit
intake pressure sensor plausibility
intake pressure sensor plausibility
intake pressure sensor signal voltage too high
intake pressure sensor signal voltage too high
intake pressure sensor signal voltage too high
intake pressure sensor signal voltage too low
intake pressure sensor signal voltage too low
intake pressure sensor signal voltage too low
internal error counter fault
internal error engine shut off
internal error engine voltage monitoring
internal error engine voltage monitoring
internal voltage error
kickdown switch plausibility
lateral accelerator sensor plausibilty
leakage cylinder #1
leakage cylinder #2
leakage cylinder #3
leakage cylinder #4
leakage cylinder #5
maf sensor signal plausibility
manual transmissio coded as auto transmission
mass air flow sensor negative deviation
mass air flow sensor plausibility
mass air flow sensor plausibility air mass too high
mass air flow sensor plausibility air mass too high
mass air flow sensor plausibility air mass too low
mass air flow sensor plausibility air mass too low
mass air flow sensor plausibility signal ratio error
mass air flow sensor plausibility signal ratio too
large
mass air flow sensor plausibility signal ratio too
6
GENERAL INFORMATION

service manual. Following these procedures is very
important to the safety of the individuals perform-
ing the diagnostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If it does not, false diagnostic codes
or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the powertrain system are
intended to be serviced as an assembly only. At-
tempting to remove or repair certain system sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRBIIITMULTIMETER IS DANGEROUS. IT
CAN EXPOSE YOU TO SERIOUS OR
POSSIBLE FATAL INJURY. CAREFULLY
READ AND UNDERSTAND THE CAUTIONS
AND SPECIFICATION LIMITS.
Follow the vehicle manufacturer 's service specifi-
cations at all times.
± Do not use the DRBIIItif it has been dam-
aged.
± Do not use the test leads if the insulation is
damaged or if metal is exposed.
± To avoid electrical shock, do not touch the test
leads, tip or the circuit being tested.
± Choose the proper range and function for the
measurement. Do not try voltage or current
measurements that may exceed the rated ca-
pacity.
± Do not exceed the limits shown in the table
below:
FUNCTION INPUT LIMIT
Volts 0±500 peak volts AC
0±500 volts DC
Ohms (Resistance)* 0±1.12 megaohms
Frequency Measure
Frequency Generated0±10 kHz
Temperature ±58 ± +1100ÉF
±50 ± +600ÉC
* Ohms cannot be measured if voltage is present.
Ohms can be measured only on a non-powered
circuit.± Voltage between any terminal and ground
must not exceed 500v DC or 500v peak AC.
± Use caution when measuring voltage above
25v DC or 25v AC.
± The circuit being tested must be protected by a
10 amp fuse or circuit breaker.
± Use the low current shunt to measure circuits
up to 10 amps. Use the high current shunt to
measure circuits exceeding 10 amps.
± When testing for the presence of voltage or
current, make sure the meter is functioning
correctly. Take a reading of a known voltage or
current before accepting a zero reading.
± When measuring current, connect the meter in
series with the load.
± Disconnect the live test lead before disconnect-
ing the common test lead.
4.3 WARNINGS AND CAUTIONS
4.3.1 ROAD TEST WARNINGS
Some complaints will require a test drive as part
of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
code or symptom condition.
CAUTION: Before road testing a vehicle, be
sure that all components are reassembled.
During the test drive, do not hang the DRBIIIT
from the rear view mirror. Do not attempt to
read the DRBIIITwhile driving. Have an
assistant available to operate the DRBIIIT.
4.3.2 VEHICLE DAMAGE CAUTIONS
Before disconnecting any control module, make
sure the ignition is off. Failure to do so could
damage the module. When testing voltage or circuit
integrity at any control module, use the terminal
side (not the wire end) of the harness connector. Do
not probe through the insulation; this will damage
it and eventually cause it to fail because of corro-
sion.
Be careful when performing electrical test so as to
prevent accidental shorting of terminals. Such a
mistake can damage fuses or components. Also, a
second code could be set, making diagnosis of the
original problem more difficult.
5.0 REQUIRED TOOLS AND
EQUIPMENT
DRBIIIt(diagnostic read-out box) scan tool
vacuum gauge
ammeter
9
GENERAL INFORMATION

Symptom:
*NO RESPONSE FROM ENGINE CONTROL MODULE
POSSIBLE CAUSES
CHECK POWERS AND GROUNDS TO THE ENGINE CONTROL MODULE
K-ECM CIRCUIT SHORTED TO GROUND
K-ECM CIRCUIT SHORTED TO VOLTAGE
K-ECM CIRCUIT OPEN
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the Engine Control Module harness connectors.
Check each power and ground circuit to the module.
Were any problems found?All
Ye s!Refer to the wiring diagrams located in the service information to
help isolate an open or shorted condition. Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 2
2 Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance between ground and the K-ECM circuit.
Is the resistance below 5.0 ohms?All
Ye s!Repair the K-ECM circuit for a short to ground.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 3
3 Turn the ignition off.
Disconnect the DRBIIItfrom the DLC.
Disconnect the ECM harness connectors.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the K-ECM circuit.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Repair the K-ECM circuit for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 4
12
COMMUNICATION