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.

### DTC Descriptors

DTC B3884 02: Center Brake Light Circuit Short to Ground
DTC B3884 05: Center Brake Light Circuit Short to Voltage or Open

### 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 | -- | 1 | -- | --
Left Rear Stop/Turn Lamp Ground | -- | 1 | -- | --
Right Rear Stop/Turn Lamp Ground | -- | 1 | -- | --
1. Stop Lamps 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.

### Conditions for Running the DTC

• | Battery voltage must be between 9-16 volts.

• | Brakes APPLIED.

### Conditions for Setting the DTC

#### B3884 02

The DTC will set when the REC detects a short to ground in the CHMSL control circuit when the stop lamps are being commanded ON.

#### B3884 05

The DTC will set when the REC detects a short to voltage or an open/high resistance in the CHMSL control circuit when the stop lamps are being commanded ON.

### Actions Taken When the DTC Sets

The REC will disable the CHMSL control circuit.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists.

• | A history DTC will clear once 100 malfunction-free ignition cycles have occurred.

### 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 Testing

1. Ignition OFF, disconnect the harness connector at the CHMSL.
2. Ignition OFF, test for less than 5.0 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 Center 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.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | High Mount Stop Lamp Replacement

• | Control Module References for REC replacement, setup, and programming