P1632

Diagnostic Chart:

Schematic:

The passlock system is designed to prevent vehicle theft by allowing the ECM to disable the fuel injectors unless a correct key (voltage) code from the passlock sensor via the mechanical key is correct. The passlock system utilizes four components: the lock cylinder, passlock sensor, Body Control Module (BCM) and Engine Control Module (ECM). When the engine is cranked, the BCM will look for a password from the passlock sensor. If the password is not received within a certain amount of time or is incorrect, the BCM will send a "fuel disable password" to the ECM over the CAN link. The SECURITY telltale will flash and the engine will not be allowed to start. If the BCM receives the correct password from the passlock sensor that it has stored in memory, it will send it over the CAN link to the ECM. If the ECM passlock password it has stored in memory does not match the BCM password; or if the ECM receives an undecided password from the BCM, it will allow the engine to start then stall within 4 seconds. The SECURITY telltale will flash for 10 minutes if the ECM receives an undecided, incorrect or fuel disable password. If the password to the PCM is correct, the engine will operate normally. The password is sent continuously by the BCM to the ECM during run mode. If the password becomes lost or incorrect during the drive cycle, the vehicle will be allowed to start on succeeding ignition cycles without the aid of passlock and the SECURITY telltale will be On steady. This mode is called fail enable mode.

DTC PARAMETERS
DTC P1632 will set if the ECM receives a fuel disable password or an undecided password from the BCM

DTC P1632 diagnostic runs once per ignition cycle during engine crank

P1632 is a (type D) DTC

DIAGNOSTIC AIDS
Diagnose any BCM passlock DTCs or communication DTCs first.

If the ECM receives an undecided password from the BCM during an engine crank, the engine will start then stall. If the ECM receives a fuel disable password, the engine will not start.

Perform the security system (passlock) relearn procedure.