Circuit/System Testing

Brake Pedal Position Sensor Malfunction

1. Ignition OFF, disconnect the harness connector at the brake pedal position sensor.
2. Ignition ON, verify that a test lamp does not illuminate between the low reference circuit terminal A and ground.
   • If the test lamp illuminates, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal C and ground.
   • If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
   • If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, replace the brake pedal position sensor.

Stop Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate stop lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5 Ω between the ground circuit terminal C and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal A and ground.
4. Ignition ON, command the appropriate Stop/Turn Signal Lamp 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 voltage. If the circuit tests normal, replace the BCM.
   • 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 BCM.
5. If all circuits test normal, replace the stop lamp.

Center High Mount Stop Lamp Malfunction

1. Ignition OFF, disconnect the center high mount stop lamp relay.
2. Ignition OFF, exterior lamps OFF, test for less than 5 Ω between the ground circuit terminal 2 and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 5 and ground.
   • If the test lamp illuminates, test the control circuit for a short to voltage.
4. Verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 5 for a short to ground. If the circuit tests normal, test or replace the CHMSL relay.
5. Ignition OFF, disconnect the harness connector at the center high mount stop lamp.
6. Ignition OFF, exterior lamps OFF, test for less than 5 Ω between the ground circuit terminal B and ground.
   • If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the center high mount stop lamp.
8. Connect a 10 A fused jumper wire between the B+ circuit terminal 3 and the control circuit terminal 5. Verify the center high mount stop lamp illuminates.
   • If the center high mount stop lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the center high mount stop lamp.
9. Connect a test lamp between the control circuit terminal 1 and ground.
10. Ignition ON, turn the test lamp ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the selected states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    • 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 BCM.
11. If all circuits test normal, test or replace the center high mount stop lamp relay.