Circuit Description
A Class 2 serial data communications system is used on this vehicle to allow various modules to communicate and share information with each other. This allows the vehicle electrical wiring to be reduced and the transmission and reception of module signals over a single wire. If a module cannot respond to the PCM, a DTC is stored.
Conditions for Setting the DTC
The PCM cannot communicate with the Body Control Module(BCM) for 15 seconds after having previously established communications with the BCM for that ignition cycle.
Action Taken When the DTC Sets
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | A scan tool can clear the MIL/DTCs. |
Diagnostic Aids
| • | An intermittent problem may be caused by the following conditions: |
| - | Poor electrical connection |
| - | Rubbed through wire insulation |
| - | A wire that is broken inside the wire insulation |
| • | Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed electrical connectors |
| - | Damaged terminals |
| - | A poor terminal to wire connection |
| • | Install an additional ground wire from the IPC to the negative side of the battery if electrical interference is suspected. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrian OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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A scan tool that cannot display PCM data indicates that a short, or open may exist on the serial data circuit. Refer to Data Link Connector Diagnosis .
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An intermittent short on the serial data circuit could cause this DTC to set. When the fault is present, the scan tool will lose communication with the PCM and the BCM. Check for chaffed wiring or a malfunctioning BCM.
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The DTC is intermittent when a scan tool can communicate with the PCM and the BCM. DTCs within the BCM, the IPC, or the EBCM may lead to a possible cause of the intermittent problem.
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If the serial data loss occurred after a good theft password has been received, the PCM will allow the vehicle to be started on following attempts. After making the necessary repairs to the vehicle the PCM must be reprogrammed and the password learn procedure and the crankshaft position system variation procedures must be completed to allow the theft system to operate properly, Refer to the Password Learn portion of the service manual for the reprogramming procedures.
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If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
Install a scan tool. Can the scan tool display data from the PCM? | -- | |||
3 | Can the scan tool display Body Control Module (BCM) data? | -- | Go to Body Electrical | |
Check for an intermittent short or open on the BCM serial data circuit and repair as necessary. Was a repair necessary? | -- | |||
Check for DTCs or communication with the other modules and make any necessary repairs. Is the action complete? | -- | -- | ||
Does the scan tool indicate that this diagnostic ran and passed? | -- | |||
Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC table | System OK, go to Diagnostic Aids |
