N1 CHECK THE LIGHTING CONTROL MODULE
- Disconnect: LCM C2145b.
- Do the stoplamps continue to illuminate?
N2 CHECK THE BRAKE PEDAL POSITION (BPP) SWITCH
- Disconnect: BPP Switch C278.
- Do the stoplamps continue to illuminate?
N3 CHECK CIRCUIT 511 (LG) FOR SHORT TO POWER
- Disconnect: CJB Fuse 22 (15A).
- Do the stoplamps continue to illuminate?
N4 CHECK CIRCUIT 569 (DG) OR 5 (OG/LB) FOR SHORT TO POWER
- Disconnect: Multifunction Switch C202c.
- Do the stoplamps continue to illuminate?
Yes
If the high mounted stoplamp is illuminated, REPAIR circuit 569 (DG). TEST the system for normal operation.
If the right rear stoplamps are illuminated, REPAIR circuit 5 (OG/LB). TEST the system for normal operation.
If the left rear stoplamps are illuminated, GO to N5 .
No
INSTALL a new multifunction switch. REFER to Section 211-05 . TEST the system for normal operation.
Principles of Operation
The stoplamps are supplied voltage from the brake pedal position (BPP) switch. When the brake pedal is depressed, the internal switch closes and power is supplied directly to the high mounted stoplamp and the multifunction switch (which then routes the power to the rear stoplamps).
Inspection and Verification
- Verify the customer concern.
- Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart
Mechanical
Electrical
- Brake pedal position (BPP) switch
- Central junction box (CJB) fuse(s):
- Circuitry
- Stoplamp bulb(s)
- If the inspection reveals obvious concern(s) that can be readily identified, repair as necessary.
- If the concern remains after the inspection, connect the diagnostic tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
- check that the program card is correctly installed.
- check the connections to the vehicle.
- check the ignition switch position.
- If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual.
NOTE: Make sure the brake pedal is not depressed when carrying out diagnostic test.
- Carry out the DATA LINK DIAGNOSTICS TEST. If the diagnostic tool responds with:
- CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP, refer to Section 418-00 .
- NO RESP/NOT EQUIP for lighting control module (LCM), refer to Section 419-10 .
- SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out self-test diagnostics for the LCM.
- If the DTCs retrieved are related to the concern, go to the LCM Diagnostic Trouble Code (DTC) Index.
- If no DTCs related to the concern are retrieved, GO to Symptom Chart .
LCM Diagnostic Trouble Code (DTC) Index
NOTE: For a complete master list of the LCM DTCs, refer to Section 419-10 .
DTC
Description
DTC Caused By
Action
B1485
Brake Pedal Input Circuit Short to Battery
LCM
Go To Pinpoint Test N .
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