System Operation: Notes

When the ignition is turned ON, the body control module (BCM) sends the powertrain interface module (PIM) an encrypted BCM key security code. The security code is received via the slip ring or, in the event of no slip ring communication, by remote receiver. The PIM compares the received security code with the engine control module (ECM) stored security code and if the codes match, the PIM allows engine cranking and sends a separate encrypted security code to the ECM. The ECM compares this code with its stored security code and if the codes match, the ECM allows injector fuelling to continue. The PIM returns an OK TO START message, which triggers the BCM to jump from SHORT LOOP mode to the LONG LOOP mode.