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 B3445 00: Stop Lamp CircuitDTC B3884 00: Center High Mounted Stop Lamp (CHMSL) Circuit
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Body Control Module (BCM) 5 Fuse B+ | 1, 2 | 1, 2 | -- | -- |
Body Control Module (BCM) 6 Fuse B+ | 1, 2 | 1, 2 | -- | -- |
Brake Position Sensor 5-Volt Reference | C0277 06, C0890 03 | C0277 06 | 1, 2 | -- |
Stop Lamp Relay Switch B+ - European | 2 | 2 | -- | -- |
Brake Applied Signal | C0297 00 and P0571 00 | 4 | 4 | -- |
Brake Position Sensor Signal | C0277 06 | C0277 06 | C0277 07 | C0277 09 |
Center High Mounted Stop Lamp (CHMSL) Control | B3884 00 | 2, 3 | 2, 3 | -- |
Stop Lamp Relay Control - European | B3445 00 | 2, 3 | 2, 3 | -- |
Left Rear Stop/Turn Lamp Control | 1, 2 | 1, 2 | 1, 2 | -- |
Right Rear Stop/Turn Lamp Control | 1, 2 | 1, 2 | 1, 2 | -- |
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 3 | 3 | -- |
Brake Position Sensor Low Reference | -- | C0277 07 | 1, 2 | -- |
Left Rear Stop/Turn Lamp Ground | -- | 1, 2 | 1, 2 | -- |
Right Rear Stop/Turn Lamp Ground | -- | 1, 2 | 1, 2 | -- |
Stop Lamp Relay Ground - European | -- | 2 | 2 | -- |
1. Stop Lamps Malfunction - North America 2. Stop Lamps Malfunction - European 3. Center High Mounted Stop Lamp (CHMSL) Malfunction 4. Cruise Control Malfunction | ||||
Circuit/System Description
North America
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the right and left stop lamp control circuits, transmission control module (TCM), engine control module (ECM), and center high mounted stop lamp (CHMSL) control circuit.
European
The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to stop lamp relay coil side control circuit, transmission control module (TCM), engine control module (ECM), and 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 from the STOP LAMPS fuse to illuminate the rear stop lamps and trailer stop lamps.
Conditions for Running the DTC
| • | Battery voltage must be between 9-16 volts. |
| • | Brakes APPLIED. |
Conditions for Setting the DTC
DTC B3445 00
The DTC will set when the BCM detects a short to ground in the CHMSL control circuit when the stop lamps are being commanded ON.
DTC B3884 00
The DTC will set when the BCM detects a short to ground in the CHMSL control circuit when the stop lamps are being commanded ON.
Actions Taken When the DTC Sets
The BCM will not illuminate the CHMSL.
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. |
Diagnostic Aids
Important: The stop lamps will not illuminate unless the ignition is in the ON position. For more detailed information concerning stop lamp operation, refer to Exterior Lighting Systems Description and Operation.
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 Testing
- Ignition OFF, disconnect the harness connector at the CHMSL.
- Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal B and ground.
- Connect a test lamp between the control circuit terminal A and the ground circuit terminal B.
- Ignition ON, command the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, replace the CHMSL.
| ⇒ | 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, setup, and programming |
