Pinpoint Test I: All The Stoplamps Are Inoperative

Stoplamps

Pinpoint Test I: All The Stoplamps Are Inoperative

Refer to Wiring Diagram Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information [1][2]Diagrams By Number.

Normal Operation

The stoplamp switch is supplied voltage from the Battery Junction Box (BJB) fuse 24 (10A). When the brake pedal is applied, the stoplamp switch routes voltage to the Body Control Module B (BCM-B) indicating a request to turn the high mounted stoplamp and rear stoplamps on.

This pinpoint test is intended to diagnose the following:

- Fuse

- Wiring, terminals or connectors

- Stoplamp switch

- BCM-B (Body Control Module B)

PINPOINT TEST I : ALL THE STOPLAMPS ARE INOPERATIVE

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

I1 CHECK FOR VOLTAGE TO THE STOPLAMP SWITCH

- Ignition OFF.

- Disconnect: Stoplamp Switch C278.

- Measure the voltage between the stoplamp switch C278-1, circuit SBB24 (VT/RD), harness side and ground.





Is the voltage greater than 10 volts?

Yes
GO to I2.

No
VERIFY the BJB (Battery Junction Box) fuse 24 (10A) is OK. If OK, REPAIR circuit SBB24 (VT/RD) for an open. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short [1][2]Diagrams By Number.

I2 BYPASS THE STOPLAMP SWITCH

- Connect a fused jumper wire between the stoplamp switch C278-1, circuit SBB24 (VT/RD), harness side and the stoplamp switch C278-4, circuit CCB08 (VT/WH), harness side.





Are the stoplamps illuminated?

Yes
REMOVE the jumper wire. INSTALL a new stoplamp switch. REFER to Stoplamp Switch . TEST the system for normal operation.

No
REMOVE the jumper wire. GO to I3.

I3 CHECK FOR VOLTAGE TO THE BCM-B (Body Control Module B)

- Connect: Stoplamp Switch C278.

- Disconnect: BCM-B (Body Control Module B) C4368A.

- While applying the brake pedal, measure the voltage between the BCM-B (Body Control Module B) C4368A-19, circuit CCB08 (VT/WH), harness side and ground.





Is the voltage greater than 10 volts?

Yes
GO to I4.

No
REPAIR circuit CCB08 (VT/WH) for an open. TEST the system for normal operation.

I4 CHECK FOR CORRECT BCM-B (Body Control Module B) OPERATION

- Disconnect all the BCM-B (Body Control Module B) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the BCM-B (Body Control Module B) 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-B (Body Control Module B). 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.