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

Instrument Cluster and Panel Illumination

Pinpoint Tests

Pinpoint Test B: 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

The instrument panel dimmer switch provides variable voltage to the Instrument Cluster (IC).

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- IC

PINPOINT TEST B: 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.

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 IC VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

- Ignition OFF.
- Disconnect: IC C220a.
- Place the headlamp switch in the PARKING LAMPS ON position.
- Rotate the instrument panel dimmer switch to the full illumination position.
- Measure the voltage between the IC C220a-11, circuit VLN18 (BU/WH), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to B2.

No
REPAIR circuit VLN18 (BU/WH) for an open. TEST the system for normal operation.

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B2 CHECK THE IC GROUND CIRCUIT FOR AN OPEN

- Place the headlamp switch in the OFF position.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the IC C220a-1, circuit GD161 (BK/YE), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
CHECK the IC illumination bulbs. If OK, GO to B3.

No
REPAIR circuit GD161 (BK/YE) for an open. TEST the system for normal operation.

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B3 CHECK FOR CORRECT IC OPERATION

- Disconnect all the IC connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins

- Connect all the IC 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 IC. REFER to Instrumentation and Warning Chimes Instrument Cluster (IC). 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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