Circuit Description
The PCM uses the serial data circuit to communicate with various other devices and systems in the vehicle. The PCM ensures that communication remains established by monitoring the serial data circuit for state of health messages from the other devices using the circuit. If the PCM detects a loss of the state of health serial data message from the Body Function Controller (BFC), DTC P1610 will be set.
Conditions for Running the DTC
| • | The ignition is on. |
| • | System voltage is greater than 8.2 volts. |
Conditions for Setting the DTC
The PCM is detecting a loss of serial data communications with the BFC for longer than 5 seconds.
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 Freeze Frame and Failure Records buffers. |
| • | 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. |
| • | DTCs can be cleared by using a scan tool. |
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following conditions:
| • | Intermittent short circuit on the serial data circuit. |
| Refer to Data Link Communications Description in Data Link Communications and check all related wiring for an intermittent short to ground or short to voltage. |
| • | Poor connection. |
| Inspect the PCM and the affected control module harness and related connectors for improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. |
| Inspect the wiring harness for damage. Check for an intermittent short or open circuit in the wiring harnesses related to the affected control module, including the ignition positive voltage, battery positive voltage, ground, and serial data circuits. |
Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the conditions.
Attempting to start the vehicle by bypassing the Theft Deterrent system or substituting parts without performing the password learn procedure may set a DTCP1631.
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 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.
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An intermittent short on the EBCM serial data circuit could cause this DTC to set. When the fault is present, the scan tool will lose communication with the PCM. Check for chaffed wiring or a malfunctioning EBCM.
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The DTC is intermittent when a scan tool can communicate with the PCM. DTCs within the BFC or EBCM may lead to a possible cause of the intermittent problem.
If the serial data loss occurred after a good theft password has been received, the PCM must be reprogrammed and the password learn and the crankshaft position variation learn procedures must be completed to allow the theft system to operate properly.
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If no faults have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Was the Powertrain OBD System Check performed? | -- | |||
Install a scan tool. Can the scan tool display data from the PCM? | -- | |||
3 | Check for a poor connection, open, or shorted serial data circuit to the Body Control Module (BCM) and repair as necessary. Was a repair necessary? | -- | ||
Check for an intermittent short on the EBCM 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? | -- | -- | ||
6 |
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 | System OK |
