Circuit/System Testing
WARNING: This page is about a different car, the 2007 Cadillac XLR. However, it is still accessible from the selected car via links, so may be relevant.
Interior Backlighting Malfunction
- Ignition ON, install a scan tool and observe the park lamps signal parameter in the IPC data list while turning the parks lamps ON and OFF. The reading should change between OFF and ON.
- If the parameter is always ON, test the park lamp supply voltage circuit at connector C1 terminal A16 for a short to voltage. If the circuit tests normal, replace the IPC.
- If the parameter is always OFF, test the park lamp supply voltage circuit at connector C1 terminal A16 for a short to ground or and open/high resistance. If the circuit tests normal, replace the IPC.
- Ignition OFF, disconnect the harness connector at the component with the inoperative backlighting.
- Test for less than 1 ohm of resistance between the ground circuit and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the backlight lamp control circuit and ground.
- Command the park lamps ON and OFF with the park lamps switch. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the control module associated with the inoperative backlight.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the control module associated with the inoperative backlight.
- If all circuits test normal, test or replace the component with the inoperative backlighting.
Dimmer Switch Malfunction
- Ignition OFF, disconnect the harness connector at the dimmer/head up display (HUD) switch.
- Test for less than 1 ohm of resistance between the ground circuit terminal 1 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the IPC.
- Ignition ON, verify the scan tool dim select switch parameter is INACTIVE.
- If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the IPC.
- Install a 3A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool dim select switch parameter is ACTIVE.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.
- Verify the scan tool dim down switch parameter is INACTIVE.
- If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the IPC.
- Install a 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool dim down switch parameter is ACTIVE.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.
- Verify the scan tool dim up switch parameter is INACTIVE.
- If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the IPC.
- Install a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool dim up switch parameter is ACTIVE.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.
- If all circuits test normal, test or replace the dimmer/head up display (HUD) switch.