Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
MISC IGN Fuse B+ Supply | 1 | 1 | -- | -- |
Stop Lamp Switch 12V Reference | B3445 00 | 3 | -- | -- |
STOP LAMPS Fuse B+ Supply | 1 | 1 | -- | -- |
Left Outage Detection Signal | 1 | 1 | 1 | -- |
Left Outage Detection Signal -- European | 4 | 4 | 4 | -- |
Right Outage Detection Signal | 1 | 1 | 1 | -- |
Right Outage Detection Signal -- European | 4 | 4 | 4 | -- |
Stop Lamp Switch Signal | -- | 3 | 3 | -- |
Stop Lamp Switch Control | 1 | 1 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Control | B3884 00 | 2 | 2 | -- |
Left Lower Tail/Stop and Turn Signal Lamp Control | 1 | 1 | 1 | -- |
Left Upper Tail/Stop and Turn Lamp Control | 1 | 1 | 1 | -- |
Left Tail Lamp Control Circuit Board Control | 1 | 1 | 1 | -- |
Left Tail Lamp Control Circuit Board Control -- European | 4 | 4 | 4 | -- |
Right Lower Tail/Stop and Turn Signal Lamp Control | 1 | 1 | 1 | -- |
Right Upper Tail/Stop and Turn Signal Lamp Control | 1 | 1 | 1 | -- |
Right Tail Lamp Control Circuit Board Control | 1 | 1 | 1 | -- |
Right Tail Lamp Control Circuit Board Control -- European | 4 | 4 | 4 | -- |
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 2 | -- | -- |
Left Upper Tail/Stop and Turn Signal Lamp Ground | -- | 1 | -- | -- |
Left Tail Lamp Control Circuit Board Ground | -- | 1 | -- | -- |
Left Lower Tail/Stop and Turn Signal Lamp Ground | -- | 1 | -- | -- |
Left Tail/Stop Lamp Ground | -- | 1 | -- | -- |
Left Tail Lamp Circuit Board Ground -- European | -- | 4 | -- | -- |
Right Lower Tail/Stop and Turn Signal Lamp Ground | -- | 1 | -- | -- |
Right Lower Tail/Stop and Turn Signal Lamp Ground | -- | 1 | -- | -- |
Right Tail Lamp Control Circuit Board Ground | -- | 1 | -- | -- |
Right Tail/Stop Lamp Ground | -- | 1 | -- | -- |
Right Tail Lamp Circuit Board -- European | -- | 4 | -- | -- |
| ||||
Circuit/System Description
North American or European
The stop lamp switch is used to sense the action of the driver application of the brake pedal. The body control module (BCM) provides a low reference signal and a B+ reference voltage to the stop lamp switch. When the stop lamp switch contacts close indicating the brakes have been applied, the BCM will apply battery voltage to stop lamp relay control circuit and the center high mounted stop lamp (CHMSL). When the stop lamp relay receives battery voltage from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage to the STOP LAMPS fuse to illuminate the left and right stop lamps.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, observe the scan tool Stop Lamp Relay Command parameter while pressing and releasing the brake pedal. The reading should change between ON and OFF..
- Ignition ON, observe the left, right and center high mount stop lamps while pressing and releasing the brake pedal. The stop lamps should turn ON and OFF.
| ⇒ | If not the specified value, refer to the Stop Lamp Switch Malfunction. |
| ⇒ | If the left and or right stop lamps are always ON or OFF, refer to the Stop Lamp Malfunction. |
| ⇒ | If the center high mount stop lamp is always ON or OFF, refer to the Malfunction. |
Circuit/System Testing
Stop Lamp Switch Malfunction
- Ignition OFF, disconnect the harness connector at the stop lamp switch.
- Ignition ON, test for battery voltage between the 12-volt reference circuit terminal C and ground.
- Verify the scan tool Stop Lamp Switch Status parameter is approximately 1023 counts.
- Install a 3A fused jumper wire between the signal circuit terminal D and the 12-volt reference circuit terminal C. Verify the scan tool Stop Lamp Switch Status parameter is 1 count.
- If all circuits test normal, test or replace the stop lamp switch.
| ⇒ | If less than the specified range, test the 12-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
| ⇒ | If not the specified value, test the signal circuit terminal D for a short to voltage. If the circuit tests normal, replace the BCM. |
| ⇒ | If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM. |
Stop Lamp Malfunction
- Ignition OFF, disconnect the harnes connector X4 at the BCM.
- Ignition ON, verify a test lamp illuminates between the stop lamp B+ terminal 4 and ground.
- Connect the harnes connector X4 at the BCM.
- Ignition OFF, disconnect the harness connector at the appropriate stop lamp.
- Test for less than 5.0 ohms between the listed ground circuit terminal below and ground.
- Connect a test lamp between the listed stop lamp control circuit terminal and ground circuit terminal.
- Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the appropriate stop lamp.
| ⇒ | If the test lamp does not illuminate, and the STOP LAMPS fuse tests normal, test the B+ circuit for a short to ground or an open/high resistance. |
| • | Tail/Stop and Turn Signal Lamp -- Left and Right -- Upper and Lower terminal GRD -- with Z75 - E52 |
| • | Tail Lamp Circuit Board -- Left and Right terminal D -- with Z75 + E52 and European |
| • | Tail/Stop Lamp -- Left and Right terminal GRD -- with X88 |
| • | Tail/Stop Lamp -- Left and Right terminal G -- Z88 |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| • | Tail/Stop and Turn Signal Lamp -- Left and Right -- Upper and Lower terminal MJR -- with Z75 - E52 |
| • | Tail Lamp Circuit Board -- Left and Right terminal E -- with Z75 + E52 and European |
| • | Tail/Stop Lamp -- Left and Right terminal MJR -- with X88 |
| • | Tail/Stop Lamp -- Left and Right terminal A -- Z88 |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. |
CHMSL Malfunction
- Ignition OFF, disconnect the harness connector X4 at the BCM.
- Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 4 and ground.
- Reconnect the harness connector X4 at the BCM.
- Ignition OFF, disconnect the harness connector at the center high mounted stop lamp (CHMSL).
- Test for less than 5.0 ohms between the ground circuit terminal B and ground.
- Connect a test lamp between the stop lamp control circuit terminal A and ground circuit terminal B.
- Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the CHMSL.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground. |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, programming, and setup. |
