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 Descriptor
DTC B3445 00: Stop Lamp CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Body Control Module (BCM) VB4 Fuse B+ | 1 | 1 | -- | -- |
Stop Lamp Switch B+ Voltage Reference | B1395 03, B3600 03 | 1 | 1 | -- |
Stop Lamp Relay Switch B+ | 1 | 1 | -- | -- |
Stop Lamp Switch Signal | 1 | 1 | 1 | -- |
Stop Lamp Relay Control | B3445 00 | 1 | 1 | -- |
Tail/Stop Lamp Control - Left | 1 | 1 | 1 | -- |
Tail/Stop Lamp Control - Right | 1 | 1 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 2 | -- | -- |
Tail/Stop Lamp Ground - Left | -- | 1 | -- | -- |
Tail/Stop Lamp Ground - Right | -- | 1 | -- | -- |
Stop Lamp Relay Ground | -- | 1 | -- | -- |
1. Stop Lamps Malfunction 2. Center High Mounted Stop Lamp (CHMSL) Malfunction | ||||
Circuit/System Description
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 LP fuse to illuminate the left and right stop lamps.
Conditions for Running the DTC
| • | Battery voltage must be between 9-16 volts. |
| • | Brakes APPLIED. |
Conditions for Setting the DTC
The DTC will set when the BCM detects a short to ground in the stop lamp relay control circuit when the stop lamps are being commanded ON.
Action Taken When the DTC Sets
The BCM will not illuminate the stop lamps.
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
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 stop lamp relay.
- Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal 86 and ground.
- Disconnect the harness connector at the CHMSL.
- Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal 2 and ground.
- Connect a test lamp between the control circuit terminal 1 and the ground circuit terminal 2.
- 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.
- Ignition OFF, connect the stop lamp relay.
- Ignition ON, command the stop lamps ON and OFF by applying and releasing the brake pedal. The stop lamps should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the CHMSL.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | 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. |
| ⇒ | If the stop lamps do not turn ON and OFF when commanded, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the stop lamp relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
