DaimlerChrysler Jeep Grand Cherokee 2002, Service Manual

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Symptom List:
P1242-CAN BUS MESSAGE MISSING
P1242-CAN BUS MESSAGE MISSING FROM TCM
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P1242-CAN BUS MESSAGE
MISSING.
When Monitored and Set Condition:
P1242-CAN BUS MESSAGE MISSING
When Monitored: With the ignition on.
Set Condition: The ECM detects an open on the CAN Bus circuit.
P1242-CAN BUS MESSAGE MISSING FROM TCM
When Monitored: With the ignition on.
Set Condition: The ECM does not receive an expected CAN Bus message from the TCM.
POSSIBLE CAUSES
CAN C BUS CIRCUITS OPEN
CAN C BUS CIRCUITS SHORTED TO GROUND
CAN C BUS CIRCUITS SHORTED TOGETHER
ENGINE CONTROL MODULE
TRANSMISSION CONTROL MODULE
INTERMITTENT CONDITION
ABS - TERMINATING RESISTOR
ECM - CAN C BUS CIRCUIT
TCM - TERMINATING RESISTOR
TEST ACTION APPLICABILITY
1 NOTE: This DTC indicates a communication problem between the TCM and
the ECM.
Turn the ignition on.
With the DRB, erase ECM DTCs.
Perform several engine run cycles, turning the ignition off for at least 20 seconds
between each engine run cycle.
With the DRBIII
t
, read the ECM DTCs.
Did this DTC set again?
All
Yes
→
Go To 2
No
→
Go To 8
174
DRIVEABILITY - DIESEL
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