Circuit Description
A Class 2 serial data communications system is used on this vehicle in order 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 is unable to communicate with the EBCM for a duration of 15 seconds after previously establishing communications with the EBCM during the present ignition cycle. |
| • | The Ignition switch is in the CRANK position for 15 seconds and the engine is not rotating due to a one of the following conditions: |
| - | A starter malfunction exists. |
| - | An electrical malfunction exists. |
| - | The clutch pedal is not depressed (manual transmission). |
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 |
| - | Worn wire insulation |
| - | A wire that is broken inside the wire insulation |
| • | Any circuitry that is suspected as causing the intermittent complaint should be thoroughly inspected 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
The numbers below refer to the step numbers on the Diagnostic Table.
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The Powertrain 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 malfunction occurred. The information is then stored in the scan tool for later reference.
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A scan tool that is unable to display PCM data indicates that a short or open may exist on the serial data circuit. Refer to Scan Tool Does Not Communicate with Class 2 Data Line .
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An intermittent short on the serial data circuit may cause this DTC to set. When the malfunction is present, the scan tool will lose communication with the PCM and the EBCM. Inspect for chaffed wiring or a malfunctioning EBCM.
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The DTC is intermittent when a scan tool can communicate with the PCM and the EBCM. DTCs with other modules may lead to a possible cause of the intermittent problem.
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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 |
|---|---|---|---|---|
1 | Did you perform the Data Link Communications Diagnostic System Check? | -- | ||
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 2.2L or Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 4.3L | ||
Can the scan tool display data from the PCM? | -- | |||
4 | Can the scan tool display EBCM data? | -- | Go to Diagnostic System Check - ABS in Antilock Brake System | |
5 | Inspect for an intermittent, short, or open electrical connection on the serial data circuit to the BCM. Repair the circuit as necessary. Was a repair necessary? | -- | ||
Inspect for DTCs or communication with the other modules. Perform any necessary repairs. Is the action complete? | -- | -- | ||
7 |
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 | Go to Diagnostic Aids |
