Circuit/System Testing
WARNING: This page is about a different car, the 2008 Isuzu Ascender, 2008 GMC Envoy, and 2008 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
In order to avoid misdiagnosis, inspect for the following:
- Verify there are no DTCs set as current. If any DTCs are set as current, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostics/repairs before proceeding with symptom based diagnostics
- Inspect the cruise control switches for any sticking or binding conditions.
- Inspect for proper operation of the stop lamps. Refer to Exterior Lighting Systems Description and Operation .
- Ignition OFF, disable the SIR system. Refer to SIR Disabling and Enabling .
- Disconnect the turn signal multifunction switch harness connector X4.
- Ignition ON, verify the Cruise Control On/Off Switch parameter displays Off.
- If the Cruise Control On/Off Switch parameter displays On, test the cruise ON switch signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Test for B+ between the turn signal multifunction switch harness connector X4 terminal A and ground.
- If the reading is less than specified, test the cruise control switch voltage supply circuit for an open or high resistance.
- Connect a 3-amp fused jumper between terminals A and B of the turn signal multifunction switch harness connector X4. Verify the Cruise Control On/Off Switch parameter displays On.
- If the Cruise On/Off Switch parameter displays Off, test the cruise control ON switch signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
- Verify the Cruise Control Resume/Accel. Switch parameter displays Off.
- If the Cruise Control Resume/Accel. Switch parameter displays On, test the cruise control resume/accel. switch signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Connect a 3-amp fused jumper between terminals A and C of the turn signal multifunction switch harness connector X4. Verify the Cruise Control Resume/Accel. Switch parameter displays On.
- If the Cruise Resume/Accel. Switch parameter displays Off, test the cruise control resume/accel. switch signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
- Verify the Cruise Control Set/Coast Switch parameter displays Off.
- If the Cruise Control Set/Coast Switch parameter displays On, test the cruise control set/coast switch signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Connect a 3-amp fused jumper between terminals A and D of the turn signal multifunction switch harness connector X4. Verify the Cruise Control Set/Coast Switch parameter displays On.
- If the Cruise Control Set/Coast Switch parameter displays Off, test the cruise control set/coast switch signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
- If all circuits test normal, replace the cruise control switch.