| • | 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. | 
Circuit  | Short to Ground  | Open/High Resistance  | Short to Voltage  | Signal Performance  | 
|---|---|---|---|---|
Stop Lamp Switch Signal  | C0297 00  | --  | --  | --  | 
The body control module (BCM) provides a 5-volt reference voltage and a low reference signal to the brake pedal position sensor (BPPS). When the brake pedal is applied, the BPPS sends a variable voltage signal, that will increase as the brake pedal is applied, through the stop lamp switch signal circuit to the BCM. The BCM then applies a signal through the stop lamp switch signal circuit to the engine control module (ECM) and transmission control module (TCM).
| • | The engine must be ON. | 
| • | The brake must be applied. | 
The BCM detects a short to ground in the stop lamp switch signal circuit to the ECM and TCM.
| • | The BCM stores the DTC to memory. | 
| • | The Service Vehicle Soon indicator is commanded ON. | 
| • | The condition responsible for setting the DTC no longer exists. | 
| • | A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred. | 
Lighting Systems Connector End Views
Ignition ON, observe the scan tool Brake Applied Output Signal parameter. The reading should be On, with the brakes applied.
| ⇒ | If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit test normal, replace the BCM. | 
| ⇒ | If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the BCM. | 
| • | With LS4 -- terminal 7 | 
| • | With LZE, LZ4, or LZ8 -- terminal 9 | 
| ⇒ | If the test lamp is always OFF, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the TCM. | 
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BCM, TCM and ECM replacement, setup and programming