Circuit/System Testing

Dimmer Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+.
   • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.1 volts.
   • If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM.
4. Ignition ON, test for B+ between the I/P dimming voltage reference circuit terminal 15 and ground.
   • If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Install a 3A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool BCM Dimming Control Signal parameter is greater than 2.6 volts.
   • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the headlamp switch.

Interior Backlighting Circuit Test

1. Ignition OFF, disconnect the harness connector at the affected component.
2. Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and battery voltage.
   • PRNDL lamp terminal B
   • Global window switch terminal D
   • Transfer case control switch terminal 6
   • Headlamp switch terminal 8
   • Midgate window switch terminal D
   • Sunroof switch terminal C
   • Rear window switch terminal E
   • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the listed backlighting control circuit terminal and ground.
   • PRNDL lamp terminal A
   • Global window switch terminal E
   • Transfer case control switch terminal 5
   • Headlamp switch terminal 7
   • Midgate window switch terminal E
   • Sunroof switch terminal A
   • Rear window switch terminal A
4. Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
   • If the test lamp is always off, test the control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.
   • If the test lamp is always bright, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the affected component.

LED Dimming Circuit Test

1. Ignition OFF, disconnect the harness connector at the affected component.
2. Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and battery voltage.
   • Left steering wheel switch terminal 8
   • Right steering wheel switch terminal 1
   • Analog clock terminal 2
   • Rear wiper/washer switch terminal 1
   • DIC switch terminal 5
   • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the listed LED dimming control circuit terminal and ground.
   • Left steering wheel switch terminal 6
   • Right steering wheel switch terminal 2
   • Analog clock terminal 3
   • Rear wiper/washer switch terminal 4
   • DIC switch terminal 4
   • IPC terminal 8
   • Radio terminal 7 X1
4. Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
   • If the test lamp is always off, test the control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.
   • If the test lamp is always bright, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the affected component.

Front Door Switch Backlighting Circuit Test

1. Ignition OFF, disconnect the X4 harness connector at the door lock and side window switch.
2. Connect a 3A fused jumper wire between the low reference circuit terminal 4 and ground.
3. Connect a test lamp between the backlight supply voltage circuit terminal 13 and B+. The heated seat switch backlighting should illuminate.
   • If the switch backlighting does not illuminate, replace the heated seat switch.
4. If the switch backlighting tests normal, replace the door lock and side window switch.