Circuit/System Testing

Turn Signal/Multifunction Switch Malfunction

1. Ignition OFF, disconnect the X3 and X4 harness connectors at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal K.
   • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal B.
   • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
4. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal D.
   • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
5. Ignition ON, verify the scan tool Headlamp Switch parameter is Off.
   • If not the specified value, test the signal circuits at terminal N and terminal L for shorts to ground. If the circuits test normal, replace the instrument panel module.
6. Verify the scan tool Flash to Pass switch parameter is Inactive.
   • If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the instrument panel module.
7. Verify the scan tool High Beam Select Switch parameter is Inactive.
   • If not the specified value, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the instrument panel module.
8. Install a 3 A fused jumper wire between the signal circuit terminal N and ground. Verify the scan tool Headlamp Switch parameter is On.
   • 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 instrument panel module.
9. Install a 3 A fused jumper wire between the signal circuit terminal L and ground. Verify the scan tool Headlamp Switch parameter is On.
   • 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 instrument panel module.
10. Install a 3 A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Flash to Pass 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 instrument panel module.
11. Install a 3 A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool High Beam 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 instrument panel module.
12. If all circuits test normal, test or replace the turn signal/multifunction switch.

Headlamps Malfunction - Low Beam (T84)

1. Ignition OFF, disconnect the Low Beam Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground.
   • If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the inoperative headlamp.
6. Test for less than 5 Ω between the headlamp ground circuit terminal 2 and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the headlamp.
8. Connect a 20 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp - low beam is activated.
   • If the headlamp - low beam does not activate and the jumper wire fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp.
   • If the headlamp - low beam does not activate and the jumper wire fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the instrument panel module.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the instrument panel module.
11. If all circuits test normal, test or replace the Low Beam Relay.

Headlamps Malfunction - Low Beam (High Intensity Discharge Lamps)

1. Ignition OFF, disconnect the HID Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground.
   • If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the inoperative headlamp.
6. Test for less than 5 Ω between the headlamp ground circuit terminal 4 and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the headlamp.
8. Connect a 20 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp - low beam is activated.
   • If the headlamp - low beam does not activate and the jumper wire fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp.
   • If the headlamp - low beam does not activate and the jumper wire fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the instrument panel module.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the instrument panel module.
11. If all circuits test normal, test or replace the HID Relay.

Headlamps Malfunction - High Beam (Intellibeam)

1. Ignition ON, activate the intellibeam feature and observe the intellibeam indicator located on the inside rearview mirror. The indicator should flash 1 time to indicate the system has been activated.
   • If the indicator flashes more than 3 times, replace the inside rearview mirror.
2. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
3. Connect a test lamp between B+ and the relay control circuit terminal 3.
4. Command the High Beam Headlamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
   • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the instrument panel module.
   • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the instrument panel module.
5. Connect a test lamp between B+ and the control circuit terminal 4.
6. Ignition ON, verify the test lamp illuminates with the sunload sensor covered and the headlamp switch in the AUTO position.
   • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the instrument panel module.
   • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the instrument panel module.
7. Ignition OFF, disconnect the automatic headlamp dimming relay.
8. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground.
   • If the test lamp illuminates, test the control circuit for a short to voltage.
9. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5 Ω between the ground circuit terminal 85 and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
10. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
11. Disconnect the harness connector at the inoperative headlamp.
12. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5 Ω between the ground circuit terminal 4 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
13. Connect the harness connector at the headlamp.
14. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp - high beam is activated.
    • If the headlamp - high beam does not activate and the jumper wire fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp.
    • If the headlamp - high beam does not activate and the jumper wire fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
15. Connect a test lamp between the ground circuit terminal 85 and the control circuit terminal 86.
16. Command the Automatic Headlamp Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the inside rearview mirror.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the inside rearview mirror.
17. If all circuits test normal, test or replace the automatic headlamp dimming relay.

Headlamps Malfunction - High Beam (T84)

1. Ignition OFF, disconnect the High Beam Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground.
   • If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the inoperative headlamp.
6. Test for less than 5 Ω between the headlamp ground circuit terminal 2 and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the headlamp.
8. Connect a 10 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp - high beam is activated.
   • If the headlamp - high beam does not activate and the jumper wire fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp.
   • If the headlamp - high beam does not activate and the jumper wire fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the instrument panel module.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the instrument panel module.
11. If all circuits test normal, test or replace the High Beam Relay.

Headlamps Malfunction - High Beam (with High Intensity Discharge Headlamps)

1. Ignition OFF, disconnect the High Beam Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground.
   • If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
5. Disconnect the harness connector at the inoperative headlamp.
6. Test for less than 5 Ω between the headlamp ground circuit terminal 4 and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the headlamp.
8. Connect a 10 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp - high beam is activated.
   • If the headlamp - high beam does not activate and the jumper wire fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp.
   • If the headlamp - high beam does not activate and the jumper wire fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the instrument panel module.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the instrument panel module.
11. If all circuits test normal, test or replace the High Beam Relay.