Circuit Description

After the key resistor pellet has been confirmed by the PASS-Key(R) portion of the Vehicle Theft Deterrent (VTD) system, the IPC sends a password to the PCM via the class 2 serial data bus. If password matches the password stored in the PCM, fuel will be enabled. If IPC does not send a password or if PCM does not receive it, vehicle will not start unless VTD has the fuel enabled.

If IPC and PCM loose communication with each other while engine is running, VTD system will fail-enable and allow driver to restart the vehicle on future ignition cycles until communications between the IPC and PCM are restored. If battery is disconnected during this period, vehicle will loose its fail-enabled status and will no longer start until communications has been re-established.

If IPC and PCM loose communications with each other while engine is not running, VTD system will disable fuel until communications is restored to prevent vehicle theft.

In both cases, DTC P1626 will be set. The PCM will not disable fuel injection once it has been enabled within a given ignition cycle to prevent stalling as a result of VTD system faults.