Pinpoint Test K: The Stoplamp(s) Are On Continuously
Stoplamps
Pinpoint Tests
Pinpoint Test K: The Stoplamp(s) Are On Continuously
Refer to Wiring Diagram Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information. Diagrams By Number
Normal Operation
The stoplamp switch is supplied voltage from the Body Control Module (BCM). When the brake pedal is applied, the stoplamp switch routes voltage to the PCM and back to the BCM to indicate the brake pedal is applied.
The BCM provides voltage to all the stoplamps (on independent circuits) when it detects the brake pedal is applied.
The voltage from the stoplamp switch also passes through the BCM fuse 31 (5A) and is routed to the Trailer Brake Control (TBC) module on one circuit and for a customer access use on another circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Stoplamp switch
- TBC module
- PCM
- BCM
PINPOINT TEST K: THE STOPLAMP(S) ARE ON CONTINUOUSLY
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K1 DETERMINE IF ALL THE STOPLAMPS ARE ON
- Ignition ON.
- Observe the stoplamps.
- Are all the stoplamps on?
Yes
GO to K3.
No
GO to K2.
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K2 CHECK THE STOPLAMP VOLTAGE SUPPLY CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM C2280d .
- Ignition ON.
- Does any stoplamp continue to illuminate?
Yes
If the LH rear lamp continues to illuminate, REPAIR circuit CLS18 (GY/BN) for a short to voltage. TEST the system for normal operation. If the RH rear lamp continues to illuminate, REPAIR circuit CLS19 (VT/OG) for a short to voltage. TEST the system for normal operation. If the high mounted stoplamp continues to illuminate, REPAIR circuit CLS52 (BN) for a short to voltage. TEST the system for normal operation.
No
GO to K9.
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K3 CHECK THE STOPLAMP SWITCH
- Disconnect: Stoplamp Switch C278 .
- Do the stoplamps continue to illuminate?
Yes
GO to K4.
No
INSTALL a new stoplamp switch. REFER to Stoplamp Switch Service and Repair. TEST the system for normal operation.
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K4 CHECK THE PCM
- Ignition OFF.
- Disconnect: PCM C175b (Gasoline Engine) or C1232b (Diesel Engine) .
- Ignition ON.
- Do the stoplamps continue to illuminate?
Yes
If the vehicle is equipped with an aftermarket TBC module, GO to K5. If the vehicle is not equipped with an aftermarket TBC module, GO to K6.
No
GO to K8.
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K5 CHECK THE TBC MODULE
- Ignition OFF.
- Disconnect: TBC Module C2142 .
- Ignition ON.
- Do the stoplamps continue to illuminate?
Yes
GO to K6.
No
INSTALL a new TBC module. TEST the system for normal operation.
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K6 CHECK THE CUSTOMER ACCESS CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM C2280f .
- Ignition ON.
- Do the stoplamps continue to illuminate?
Yes
GO to K7.
No
REPAIR circuit CBP31 (BU/OG) for a short to voltage. TEST the system for normal operation.
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K7 CHECK THE STOPLAMP SWITCH INPUT AND TBC MODULE BRAKE INPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM C2280b .
- Ignition ON.
- Measure the voltage between the BCM C2280b-28, circuit CCB08 (VT/WH), harness side and ground; and between the BCM C2280b-4, circuit CBP31 (BU/OG), harness side and ground
- Is any voltage present?
Yes
REPAIR circuit CCB08 (VT/WH) or circuit CBP31 (BU/OG) for a short to voltage as necessary. TEST the system for normal operation.
No
GO to K9.
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K8 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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K9 CHECK FOR CORRECT BCM OPERATION
- Disconnect all the BCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new BCM. REFER to Multifunction Electronic Modules Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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