Diagnostic Test

CHECK FOR AN ACTIVE DTC
NOTE:
Verify that the Brake Switch is installed correctly on the vehicle before proceeding.
1. Turn the ignition on.
2. With the scan tool, read ABS DTCs and record on the repair order.
3. With the scan tool, erase DTCs.
4. Press the brake pedal firmly and release.
5. With the scan tool, read ABS DTCs.
  Is the DTC active?
  
  Yes
  - Go To 2
  No
  - The condition or conditions that originally set this DTC are not present at this time. Using the appropriate SYSTEM WIRING DIAGRAMS as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension and repair as necessary. If no problems are found, test complete.
  - Perform the ABS INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .
CHECK FOR BODY CONTROL MODULE (BCM) DTCS
1. Refer to the recorded DTCs.
  Are there any BCM or Communication related DTCs active or pending?
  
  Yes
  - Perform the appropriate diagnostic procedure. Refer to DTC TROUBLESHOOTING .
  No
  - Go To 3
STOP LAMP SWITCH OPERATION
1. Start the engine.
2. Using the scan tool, monitor the brake pedal switch status while pressing the brake pedal and releasing.
  Is the Stop Lamp Switch operating correctly?
  
  Yes
  - Go To 4
  No
  - Check for correct Stop Lamp Switch Installation. Refer to SWITCH, STOP LAMP, REMOVAL AND INSTALLATION .
  - Go To 6
CHECK THE (B135) BRAKE SIGNAL 1 CIRCUIT FOR A SHORT TO GROUND OR OPEN
NOTE:
The (B135) Brake Signal 1 circuit is normally OPEN when the brake pedal is NOT PRESSED.
1. Turn the ignition off.
2. Disconnect the BCM C4 harness connector.
3. With the Brake Pedal PRESSED, measure the voltage of the (B135) Brake Signal 1 circuit at the BCM C4 harness connector.
  Is the voltage above 10 volts?
  
  Yes
  - Go To 5
  No
  - Repair the (B135) Brake Signal 1 circuit for an open or short to ground.
    NOTE:
    Check for loose terminals at Fuse 51 in the PDC. Repair as necessary.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
CHECK THE (B134) BRAKE SIGNAL 2 CIRCUIT FOR A SHORT TO GROUND OR OPEN
NOTE:
The (B134) Brake Signal 2 circuit is normally CLOSED when the brake pedal is NOT PRESSED.
1. Turn the ignition on.
2. With the Brake Pedal NOT PRESSED, measure the voltage of the (B134) Brake Signal 2 circuit at the BCM C4 harness connector.
  Is the voltage above 10 volts?
  
  Yes
  - Go To 6
  No
  - Repair the (B134) Brake Signal 2 circuit for an open or short to ground.
    NOTE:
    Check for loose terminals at Fuse 51 in the PDC. Repair as necessary.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
STOP LAMP SWITCH
1. Turn the ignition off.
2. Replace the Stop Lamp Switch in accordance with the Service Information. Refer to SWITCH, STOP LAMP, REMOVAL AND INSTALLATION .
3. Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
4. Turn the ignition on.
5. Press and release the brake pedal.
6. With the scan tool, read ABS DTCs.
  Is the DTC active?
  
  Yes
  - Replace the Body Control Module (BCM) in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL AND INSTALLATION .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Test complete.