Circuit/System Testing

DRL Inoperative

1. Disconnect the harness connector at the ambient light sensor.
2. Install a 3A fused jumper wire between the signal circuit and the low reference circuit.
3. Verify the scan tool Day/Night Status parameter is Day.
   • If not the specified value, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, replace the ambient light sensor.

ALC Inoperative

1. Disconnect the harness connector at the ambient light sensor.
2. Verify the scan tool Day/Night Status parameter is Night.
   • If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
3. If all circuits test normal, replace the ambient light sensor.

Low Beam Headlamps Inoperative

1. Ignition OFF, disconnect the LO/BEAM relay.
2. Ignition ON, verify that a test lamp illuminates between the relay switch B+ circuit and ground.
   • If the test lamp does not illuminate, replace the underhood fuse block.
3. Connect a 10A fused jumper wire between the relay switch B+ circuit and the relay controlled output circuit. Verify the low beam headlamps are activated.
   • If the low beam headlamps do not activate, replace the underhood fuse block.
4. Replace the LO/BEAM relay.

High Beam Headlamps Inoperative

1. Ignition OFF, disconnect the HI/BEAM relay.
2. Ignition ON, verify that a test lamp illuminates between the relay switch B+ circuit and ground.
   • If the test lamp does not illuminate, replace the underhood fuse block.
3. Connect a 10A fused jumper wire between the relay switch B+ circuit and the relay controlled output circuit. Verify the high beam headlamps are activated.
   • If the high beam headlamps do not activate, replace the underhood fuse block.
4. Replace the HI/BEAM relay.

Headlamp Switch Malfunction

1. Ignition OFF, disconnect the X1 harness connector at the turn signal/multifunction switch.
2. Verify that a test lamp illuminates between the ground circuit terminal 1 and B+.
   • If the test lamp does not illuminate, test the ground circuit terminal 1 for a short to voltage or an open/high resistance.
3. Ignition ON, install a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Headlamp On Switch parameter is Active.
   • If not the specified value, test the signal circuit terminal 2 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Headlamp Off Switch parameter is Active.
   • If not the specified value, test the signal circuit terminal 4 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Ignition OFF, disconnect the X2 harness connector at the turn signal/multifunction switch.
6. Verify that a test lamp illuminates between the ground circuit terminal B and B+.
   • If the test lamp does not illuminate, test the ground circuit terminal B for a short to voltage or an open/high resistance.
7. Ignition ON, install a 3A fused jumper wire between the signal circuit terminal C and ground. Verify the scan tool Flash to Pass Switch parameter is Active.
   • If not the specified value, test the signal circuit terminal C for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
8. Install a 3A fused jumper wire between the signal circuit terminal D and ground. Verify the scan tool High Beam Select Switch parameter is Active.
   • If not the specified value, test the signal circuit terminal D for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
9. Install a 10A fused jumper wire between the signal circuit terminal F and ground. Verify the low beam headlamps are activated.
   • If the low beam headlamps do not activate, test the signal circuit terminal F for a short to voltage or an open/high resistance.
10. If all circuits test normal, replace the turn signal/multifunction switch.

Headlamp Inoperative - One

1. Place the headlamp switch in the ON position of the inoperative lamp.
2. Disconnect the harness connector of the inoperative lamp.
3. Verify that a test lamp illuminates between the ground circuit terminal B and B+.
   • If the test lamp does not illuminate, test the ground circuit terminal B for a short to voltage or an open/high resistance.
4. Test the voltage supply circuit terminal A for a short to ground or an open/high resistance.

High Beam Indicator Inoperative

1. Command the instrument panel Display Test ON with a scan tool. The high beam indicator should illuminate.
   • If the high beam indicator does not illuminate, replace the instrument panel cluster.
2. If all circuits test normal, replace the BCM.