Pinpoint Test C: One High Beam Headlamp Is Inoperative

Headlamps

Pinpoint Test C: One High Beam Headlamp Is Inoperative

Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number

Normal Operation

When a request for the high beams is received by the Lighting Control Module (LCM), the LCM provides voltage through circuit 1337 (VT/YE) to the LH headlamp and through circuit 1335 (YE/WH) to the RH headlamp. Ground is shared with the low beam headlamps.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- LCM



PINPOINT TEST C: ONE HIGH BEAM HEADLAMP 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 LOW BEAMS


- Ignition OFF.

- NOTE: Make sure the multifunction switch is in the LOW BEAM position.

- Place the headlamp switch in the HEADLAMPS ON position.
- Do the low beams operate correctly?

Yes
GO to C2.

No
Go To Pinpoint Test B. Pinpoint Test B: One Low Beam Headlamp Is Inoperative

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C2 CHECK THE HEADLAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN OR SHORT TO GROUND


- Disconnect: Inoperative Headlamp.
- Disconnect: LCM C2145c.
- Measure the resistance between the inoperative headlamp, harness side and the LCM, harness side; and between the inoperative headlamp, harness side and ground as follows:





- Is the resistance less than 5 ohms between the headlamp and the LCM, and greater than 10,000 ohms between the headlamp and ground?

Yes
GO to C3.

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

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C3 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. 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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