Cruise Control System Diagnosis

Circuit Description
The cruise control module signals the PCM when the cruise system is active. The PCM supplies a B+ voltage to the cruise control engage circuit. The cruise control module grounds the signal circuit to the PCM when the cruise is enabled. The PCM then modifies transmission shift patterns based on the cruise conditions. The PCM also sends a class 2 message to the IPC to illuminate the cruise indicator.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

^ The following may cause an intermittent:
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
^ For an intermittent, refer to Symptoms. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers on the Diagnostic Table
5. This step is inspecting for a short to ground
9. This step is inspecting the Cruise Engage circuit for a short to another PCM circuit.
15. If no continuity is displayed on the DMM, inspect for a poor connection at the C100 (16 way black) connector. Refer to Intermittents and Poor Connections Diagnosis.