• | 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 |
---|---|---|---|---|
I/P Voltage Reference - Stop Lamp Switch | B1395 03, B3600 03 | 2 | -- | -- |
Stop Lamp Switch Signal | B1395 03, B3600 03 | 2 | 2 | -- |
CHMSL Control | B3445 00 | 1 | 1 | -- |
Left Rear Stop/Turn Lamp Control | 1 | 1 | 1 | -- |
Right Rear Stop/Turn Lamp Control | 1 | 1 | 1 | -- |
Stop Lamp Relay Control | B3884 00 | 1 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 1 | -- | -- |
Left Rear Stop/Turn Lamp Ground | -- | 1 | -- | -- |
Right Rear Stop/Turn Lamp Ground | -- | 1 | -- | -- |
Stop Lamp Relay Ground | -- | 1 | -- | -- |
1. Stop Lamp Malfunction 2. Stop Lamp Switch Malfunction |
The BCM controls the stop lamps based on the input from the stop lamp switch. When the BCM detects the brake pedal is depressed, B+ is applied to the stop lamp relay control circuit energizing the Stop Lamp PCB Relay. With the relay energized, B+ is applied to the stop/turn lamp supply voltage circuits illuminating both stop lamps. At the same time the BCM applies B+ to the center high mounted stop lamp (CHMSL), transmission control module (TCM), and engine control module (ECM).
Exterior Lighting Systems Description and Operation
Control Module References for scan tool information
⇒ | If the rear turn signals do not operate as specified, refer to Turn Signal Lamps and/or Indicators Malfunction. |
⇒ | If the Stop Lamp Switch Status reading does not change between the specified values, refer to the Stop Lamp Switch Malfunction. |
⇒ | If one or more stop lamps do not illuminate, refer to Stop Lamp Malfunction |
⇒ | If the stop lamps illuminate, but the CHMSL does not illuminate, refer to the Center High Mounted Stop Lamp Malfunction. |
⇒ | If the test lamp does not turn ON or remains ON at either test point, refer to the Auxiliary Stop Lamps PCB Relay Test. |
⇒ | If the test lamp turns ON and OFF as the brake pedal is pressed and released, but the auxiliary stop lamps are inoperative, refer to the Auxiliary Stop Lamp Malfunction. |
⇒ | If the test lamp does not illuminate, test the 12-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If greater than the specified value, test the signal circuit terminal D for a short to voltage. If the circuit tests normal, replace the BCM. |
⇒ | If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | 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 test lamp illuminates, test the control circuit for a short to voltage. |
⇒ | If the stop lamps do not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block. |
⇒ | 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 underhood fuse block. |
⇒ | 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 underhood fuse block. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, setup, and programming |