For 1990-2009 cars

### 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
--- | --- | --- | --- | ---
Brake Pedal Position Sensor Signal - terminal 2 | B0655 5a | B0655 5a | B0655 5a | --
Brake Pedal Position Sensor Signal - terminal 4 | B0655 5a | B0655 5a | B0655 5a | --
Brake Pedal Position Sensor Control - terminal 1 | 1 | 1 | -- | --
Brake Pedal Position Sensor Control - terminal 3 | 1 | 1 | -- | --
Center High Mounted Stop Lamp (CHMSL) Control | B3884 02 | B3884 05 | B3884 05 | --
Left Rear Stop/Turn Lamp Control | 1 | 1 | 1 | --
Right Rear Stop/Turn Lamp Control | 1 | 1 | 1 | --
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 2 | -- | --
Left Rear Stop/Turn Lamp Ground | -- | 1 | -- | --
Right Rear Stop/Turn Lamp Ground | -- | 1 | -- | --
1. Stop Lamps Malfunction 2. High Mounted Stop Lamp Malfunction

### Circuit/System Description

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor receives B+ voltage from the underhood electrical center (UEC) from the F16 fuse. When the brake pedal is applied, the brake pedal position sensor switch contacts close. With the switch contacts closed, B+ voltage flows through the brake pedal position sensor signal circuit to the rear electrical center (REC), electronic brake control module (EBCM), engine control module (ECM), shift lock solenoid, and transmission control module (TCM). The REC responds by applying voltage to the left and right stop/turn lamp control circuits as well as the center high mounted stop lamp (CHMSL) control circuit illuminating the brake lamps.

### Reference Information

#### Schematic Reference

Exterior Lights Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Exterior Lighting Systems Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, command the stop lamps ON and OFF with a scan tool. The stop lamps should illuminate ON and OFF when changing between the commanded states.

⇒ | If the stop lamps do not illuminate when commanded, refer to Stop Lamps Malfunction.

2. Command the stop lamps ON and OFF by applying and releasing the brake pedal. The stop lamps should illuminate ON and OFF when applying and releasing the brake pedal.

⇒ | If the stop lamps do not illuminate ON and OFF as the brake pedal is applied and released, refer to Brake Pedal Position Sensor Malfunction.

### Circuit/System Testing

#### Stop Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative rear tail lamp assembly.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground.

• | Left rear tail lamp ground terminal 1 - 3 Door

• | Left rear tail lamp ground terminal 6 - 5 Door

• | Right rear tail lamp ground terminal 6 - 3 Door

• | Right rear tail lamp ground terminal 1 - 5 Door

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the appropriate control circuit terminal listed below and ground.

• | Left stop lamp control terminal 6 - 3 Door

• | Left stop lamp control terminal 4 - 5 Door

• | Right stop lamp control terminal 1 - 3 Door

• | Right stop lamp control terminal 3 - 5 Door

4. Command the stop 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 REC.

⇒ | 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 REC.

5. If all circuits test normal, replace the inoperative tail lamp circuit board.

#### High Mounted Stop Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the CHMSL.
2. Ignition OFF, test for less than 5 ohms between the ground circuit terminal 1 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 2 and ground.
4. Command the Centre Brake Light Test 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 REC.

⇒ | 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 REC.

5. If all circuits test normal, replace the CHMSL.

#### Brake Pedal Position Sensor Malfunction

1. Ignition OFF, disconnect the harness connector at the brake pedal position sensor.
2. Ignition OFF, test for greater than 11 volts between the control circuit terminal 1 and ground.

⇒ | If less than the specified value, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the UEC.

3. Ignition OFF, test for greater than 11 volts between the control circuit terminal 3 and ground.

⇒ | If less than the specified value, test the control circuit for a short to ground or an open/high resistance.

4. With a scan tool, verify the control module inputs listed below display Inactive.

• | Body exterior lighting/turn indicator system brake switch

• | Electronic brake control module (EBCM) brake light switch 1

• | Electronic brake control module (EBCM) brake light switch 2

• | Engine control module (ECM) brake switch 1

• | Engine control module (ECM) brake switch 2

• | REC brake switch

• | Transmission control module (TCM) brake switch

⇒ | If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the appropriate control module.

5. Install a 3A fused jumper wire between the control circuit terminal 1 and the signal circuit terminal 2. Verify the control module inputs listed below display Active.

• | Body exterior lighting/turn indicator system brake switch

• | Electronic brake control module (EBCM) brake light switch 2

• | Engine control module (ECM) brake switch 1

• | REC brake switch

• | Transmission control module (TCM) brake switch

⇒ | If not the specified value, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate control module.

6. Install a 3A fused jumper wire between the control circuit terminal 3 and the signal circuit terminal 4. Verify the control module inputs listed below display Active.

• | Electronic brake control module (EBCM) brake light switch 1

• | Engine control module (ECM) brake switch 2

⇒ | If not the specified value, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate control module.

7. If all circuits test normal, replace the brake pedal position sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | High Mount Stop Lamp Replacement

• | Stop Lamp Switch Replacement

• | Tail Lamp Circuit Board Replacement

• | Control Module References for EBCM, ECM, REC, or TCM replacement, setup, and programming