Pinpoint Test B: All Dimmable Switch Illumination Is Inoperative
Instrument Cluster and Panel Illumination
Pinpoint Tests
Pinpoint Test B: All Dimmable Switch Illumination Is Inoperative
Refer to Wiring Diagram Set 71, Cluster and Panel Illumination for schematic and connector information. Diagrams By Number
Normal Operation
The Lighting Control Module (LCM) receives voltage from the Central Junction Box (CJB). With the parking lamps on, the LCM generates a Pulse Width Modulated (PWM) voltage which is distributed to the dimmable components (except the HVAC module on vehicles with automatic temperature control and the Instrument Cluster (IC) which receive the brightness level from the LCM over the network).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- LCM
PINPOINT TEST B: ALL DIMMABLE SWITCH ILLUMINATION IS INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery, Mounting and Cables Battery Disconnect.
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B1 CHECK THE LCM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: LCM C2145c.
- Measure the voltage between the LCM C2145c-17, circuit 905 (GY/LB), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to B2.
No
VERIFY the CJB fuse 4 (10A) is OK. If OK, REPAIR circuit 905 (GY/LB) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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B2 BYPASS THE LCM
- NOTE: If the fuse fails, refer to the Wiring Diagrams to identify the cause of the circuit short. Diagrams By Number
- Connect a fused jumper wire between the LCM C2145c-17, circuit 905 (GY/LB), harness side and the LCM C2145c-3, circuit 484 (OG/BK), harness side.
- Do the instrument panel lamps illuminate?
Yes
GO to B3.
No
REPAIR circuit 484 (OG/BK) for an open. TEST the system for normal operation.
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B3 CHECK THE LCM GROUND CIRCUIT FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the LCM C2145a-11, circuit 676 (PK/OG), harness side and ground; and between the LCM C2145c-7, circuit 676 (PK/OG), harness side and ground.
- Are the resistances less than 5 ohms?
Yes
GO to B4.
No
REPAIR circuit 676 (PK/OG) for an open. TEST the system for normal operation.
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B4 CHECK FOR CORRECT LCM OPERATION
- Disconnect all the LCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the LCM 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 LCM. 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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