Pinpoint Test A: The Control Illumination Is Inoperative - All Hardwired Illumination

Instrument Cluster and Panel Illumination

Pinpoint Tests

Pinpoint Test A: The Control Illumination Is Inoperative - All Hardwired Illumination

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) on circuit 905 (GY/LB). Ground is provided by circuit 676 (PK/OG). With the parking lamps on, the LCM generates a Pulse Width Modulated (PWM) voltage which is distributed to the dimmable components on circuit 484 (OG/BK). Light intensity is adjusted by rotating the instrument panel dimmer switch.

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- LCM


PINPOINT TEST A: THE CONTROL ILLUMINATION IS INOPERATIVE - ALL HARDWIRED ILLUMINATION

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.

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A1 CHECK CIRCUIT 905 (GY/LB) 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 A2.

No
VERIFY the CJB fuse 21 (10A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.

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A2 CHECK CIRCUIT 676 (PK/OG) FOR AN OPEN


- Disconnect: LCM C2145a.
- 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 A3.

No
REPAIR the circuit in question. TEST the system for normal operation.

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A3 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 is still present?

Yes
INSTALL a new LCM. 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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