Pinpoint Test C: The Instrument Cluster (IC) Illumination Is Inoperative

Instrument Cluster and Panel Illumination

Pinpoint Tests

Pinpoint Test C: The Instrument Cluster (IC) Illumination Is Inoperative

Refer to Wiring Diagram Set 71, Cluster and Panel Illumination for schematic and connector information. Diagrams By Number

Normal Operation

When the side, main or parking lamps are on, the instrument panel dimmer switch (part of the headlamp switch) sends a Pulse Width Modulated (PWM) voltage to the dimmable illumination sources.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- IC


PINPOINT TEST C: THE IC 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.

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C1 CHECK THE INSTRUMENT CLUSTER ILLUMINATION CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: IC C220a.
- With the parking lamps on, rotate the instrument panel dimmer switch to the full illumination position.
- Measure the voltage between the IC C220a-24, circuit 29S-GG14 (OG), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to C2.

No
REPAIR circuit 29S-GG14 (OG) for an open. TEST the system for normal operation.

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C2 CHECK FOR CORRECT IC OPERATION


- Disconnect the IC connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IC connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new IC. REFER to Instrumentation and Warning Chimes 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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