Refer to Theft Deterrent System in Electrical Diagnosis.
Circuit Description
The vehicle theft deterrent (VTD) system is incorporated within the body control module (BCM). The powertrain control module (PCM) monitors the state of health serial data message from the theft deterrent system to ensure that the BCM to PCM communications are established. If the PCM detects a loss of the state of health message while the engine is running, DTC P1626 is set. DTC P1626 may cause a no-start condition or normal operation depending upon when the loss of system communication was detected. The engine continues to start and run if the condition that set DTC P1626 occurred after the PCM received a valid VTD password from the BCM and already allowed fuel during the ignition cycle. The engine does not start or crank if the condition that set DTC P1626 occurred before the PCM received a valid VTD password. With this condition present, the PCM inhibits fuel delivery and disables the starter until a valid VTD password is detected.
Conditions for Setting the DTC
| • | The VTD system has allowed fuel delivery. |
| • | The PCM has detected a loss of the state of health serial data message from the VTD system. |
Action Taken When the DTC Sets
The PCM stores the conditions which were present when the DTC set as Fail Records data only.
Conditions for Clearing the MIL/DTC
| • | A history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC may be cleared using the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Important: Several BCM diagnostic procedures call for disconnecting the BCM and then turning the vehicle ignition to the RUN position. These procedures result in the PCM setting DTC P1626. Therefore, DTC P1626 stored in history may be the result of previous BCM diagnostic work.
An intermittent may be caused by a faulty connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect for the following conditions:
| • | An intermittent short circuit on the serial data circuit. Refer to Data Link Connector Diagnosis in Data Link Communications. Test all of the related wiring for an intermittent short to ground or a short to voltage. |
| • | Inspect the PCM and the BCM harnesses and the related connectors for improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections. |
| • | Inspect the wiring harness for damage. Test for an intermittent short or open circuit in the wiring harnesses related to the BCM including the ignition, the battery feed, the ground, and the serial data circuits. |
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 condition.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic System Check performed? | -- | ||
2 |
Important: If a loss of DLC data has already been diagnosed using the DLC Diagnosis table, clear this DTC and continue diagnosis with the Powertrain On Board Diagnostic (OBD) System Check Important: If BCM diagnostic procedures have been performed, clear this DTC and continue diagnosis with the Powertrain On Board Diagnostic (OBD) System Check Attempt to select Vehicle Theft Deterrent system data with the scan tool. Can Vehicle Theft Deterrent system data be displayed? | -- | ||
3 |
Was a problem found? | -- | ||
4 |
Was a problem found? | -- | Refer to Diagnostic Aids | |
5 |
Was a problem found? | -- | Go to Theft Deterrent System in Electrical Diagnosis | |
6 |
Does the vehicle start and continue to run? | -- | System OK |
