P1626

Circuit Description
The Vehicle Theft Deterrent system is incorporated within the Body Control Module (BCM). The PCM monitors the state of heal the serial data message from the theft deterrent system to ensure that the PCM-BCM communications is established. If the PCM detects a loss of the state of health message while the engine is running, DTC P 1626 will be set. DTC P1626 can cause a no start condition or normal operation depending on when the loss of communication was detected. The engine will continue to start and run if the condition that set DTC P1626 occurred after the PCM received a valid theft deterrent password from the BCM and already allowed fuel during the ignition cycle. The engine will start and immediately stall if the condition that set the DTC occurred before the PCM received a valid theft deterrent password. With this condition present, the PCM will inhibit fuel delivery and disable the starter until a valid theft deterrent password is detected.

Conditions for Setting the DTC
The PCM cannot communicate with the theft deterrent system.

Action Taken When the DTC Sets
^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC
^ A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ DTC can be cleared by using a scan tool.

Diagnostic Aids
Attempting to start the vehicle by bypassing the theft deterrent system or substituting parts without performing the password learn procedure may set a DTC P1631.
If no password is received a DTC P1610, and P1631 may also be set.
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.
Any circuitry, that is suspected as causing an intermittent complaint, should be thoroughly checked for the following items:
^ Backed out terminals or improper mating.
^ Broken locks.
^ Improperly formed or damaged terminals.
^ Poor terminal to wiring connections.
^ Physical damage to the wiring harness.
^ Corrosion.
If the Body Control Module (BCM) is replaced, the PCM must be reflashed to allow the new password to be learned. The ignition must be turned off for at least 30 seconds then on for the PCM to learn the new BCM password.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
1. The Diagnostic 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.
2. A scan tool that cannot display PCM data indicates that a short exists on the serial data circuit.
6. The replacement PCM must be reprogrammed and the crankshaft position system variation procedure must be performed.

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.
7. If the serial data circuit to the Body Control Module (BCM) was not open, then the serial communication loss to the PCM lies within the BCM.
9. If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids above for additional checks and information.