Jeep Grand Cherokee WJ. Manual - part 659

TEST

ACTION

APPLICABILITY

WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?

All

Yes

→

Repair as necessary
Perform ROAD TEST VERIFICATION - VER-2.

→

Test Complete.

192

DRIVEABILITY - DIESEL

P1660-REDUNDANT EMERG. STOP POWERSTAGE DEFECTIVE —

Continued

Symptom List:

P1685-VEHICLE THEFT ALARM IMMOBILIZER SIG LOST
P1685-VEHICLE THEFT ALARM INVALID SKIM MESSAGE

Test Note:

All symptoms listed above are diagnosed using the same tests.

The title for the tests will be P1685-VEHICLE THEFT ALARM
IMMOBILIZER SIG LOST.

When Monitored and Set Condition:

P1685-VEHICLE THEFT ALARM IMMOBILIZER SIG LOST

When Monitored:

With the ignition on and the immobilizer disarmed.

Set Condition:

The ECM detects an open, short to ground, or short to voltage on the

immobilizer signal circuit.

P1685-VEHICLE THEFT ALARM INVALID SKIM MESSAGE

When Monitored:

With the ignition on.

Set Condition:

The ECM determines that the coded message from the PCM does not

match the message programmed into memory.

POSSIBLE CAUSES

CHECK FOR SKIM COMMUNICATION AND DTCS

ECM - VIN MISMATCH

PCM - VIN MISMATCH

IMMOBILIZER SIGNAL CIRCUIT SHORTED TO VOLTAGE

IMMOBILIZER SIGNAL CIRCUIT SHORTED TO GROUND

ENGINE CONTROL MODULE

IMMOBILIZER SIGNAL CIRCUIT OPEN

ENGINE CONTROL MODULE - INTERNAL SHORT

POWERTRAIN CONTROL MODULE - INTERNAL SHORT

TEST

ACTION

APPLICABILITY

Turn the ignition on.
With the DRB, check for Sentry Key Immobilizer Module communication and DTCs.
Are any SKIS problems or DTCs present?

All

Yes

→

Refer to symptom list for problems related to SKIM Communica-
tion and DTCs before continuing.
Perform ROAD TEST VERIFICATION - VER-2.

→

Go To

193

DRIVEABILITY - DIESEL

TEST

ACTION

APPLICABILITY

With the DRB, select ENGINE, then BOSCH 3.1L VM DIESEL CONTROLLER from
the menu.
Display the Vehicle Identification Number (VIN).
Compare the programmed VIN to the vehicle VIN.
Does the programmed VIN match the vehicle VIN?

All

Yes

→

Go To

→

Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.

With the DRB, select ENGINE, then JTEC CONTROLLER from the menu.
Display the Vehicle Identification Number (VIN).
Compare the programmed VIN to the vehicle VIN.
Does the programmed VIN match the vehicle VIN?

All

Yes

→

Go To

→

Replace and program the Powertrain Control Module in accor-
dance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.

Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the PCM harness connectors.
Remove the ASD/Diesel Power Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD/Diesel Power
Relay connector.
Turn the ignition on.
Measure the voltage of the Immobilizer Signal circuit.
Is the voltage below 1.0 volt?

All

Yes

→

Go To

→

Repair the Immobilizer Signal circuit for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.

NOTE: Remove the jumper wire and install the ASD/Diesel Power Relay.

Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the PCM harness connectors.
Measure the resistance between ground and the Immobilizer Signal circuit.
Is the resistance above 100 kohms?

All

Yes

→

Go To

→

Repair the Immobilizer Signal circuit for a short to ground.
Perform ROAD TEST VERIFICATION - VER-2.

Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the PCM harness connectors.
Measure the resistance of the Immobilizer Signal circuit.
Is the resistance below 5.0 ohms?

All

Yes

→

Go To

→

Repair the Immobilizer Signal circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.

194

DRIVEABILITY - DIESEL

P1685-VEHICLE THEFT ALARM IMMOBILIZER SIG LOST —

Continued

TEST

ACTION

APPLICABILITY

Turn the ignition off.
NOTE: Ensure the ECM harness connectors are connected.
Measure the amperage between ground and the Immobilizer Signal circuit in PCM
harness connector C3.
Turn the ignition on.
Is the amperage between 1.0 and 1.4 milliamps?

All

Yes

→

Go To

→

Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.

Turn the ignition off.
NOTE: Ensure all connectors are connected.
With the DRB oscilloscope function, select LAB SCOPE and set the oscilloscope to the
following specifications:
Voltage Range to +20.0V
Probe to X10
Time Range to 0.1s/Div
Turn the ignition on.
With the DRB oscilloscope lead, back probe PCM harness connector C3 cavity 16.
NOTE: A valid Immobilizer Signal voltage will cycle high and low.
Does the DRB display show the 12-volt Immobilizer Signal voltage cycling high and
low?

All

Yes

→

Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.

→

Replace and program the Powertrain Control Module in accor-
dance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.

195

DRIVEABILITY - DIESEL

P1685-VEHICLE THEFT ALARM IMMOBILIZER SIG LOST —

Continued

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