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 B3884 00: Center High Mounted Stop Lamp (CHMSL) CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
I/P Dimmer Voltage Reference | B1395 03 and B3600 03 | B1395 03, B2652 00, and B3600 03 | B1395 07 | -- |
Stop Lamp Switch Signal | B1395 03 and B3600 03 | 3 | 3 | -- |
CHMSL Control | B3884 00 | 3 | 3 | -- |
Stop Lamp Control | B3445 00 | 3 | 3 | -- |
I/P Dimmer Switch Low Reference | -- | 1 | -- | -- |
I/P Dimmer Switch Ground | -- | 2 | -- | -- |
1. Dimmer Switch Malfunction 2. Interior Backlighting Malfunction 3. Stop Lamp Switch Malfunction | ||||
Circuit/System Description
When the brake pedal is applied, the brake pedal switch normally closed contact signal circuit voltage is interrupted to the body control module (BCM). The BCM then applies a voltage to the CHMSL supply voltage circuit to the center high mounted stop lamp (CHMSL).
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The stop lamps must be commanded ON. |
Conditions for Setting the DTC
The BCM detects a short to ground in the CHMSL supply voltage circuit when the stop lamps are commanded ON.
Action Taken When the DTC Sets
The CHMSL does not illuminate.
Conditions for Clearing the DTC
| • | The conditions for setting the DTC are no longer present. |
| • | A history DTC clears after 100 malfunction-free ignition cycles. |
| • | The BCM receives the clear code command from the scan tool. |
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 center high mounted stop lamp.
- 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 center high mounted stop lamp.
| ⇒ | 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 all circuits test 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 all circuits test 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 |
