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 to the LH and RH 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 FOR VOLTAGE TO THE HIGH BEAM HEADLAMP
- Place the headlamp switch in the OFF position.
- Disconnect: Inoperative High Beam Headlamp.
- Place the headlamp switch in the HEADLAMPS ON position.
- Place the multifunction switch in the HIGH BEAM position.
- Measure the voltage between the LH high beam headlamp C1020-1, circuit 1335 (YE/WH), harness side and ground; or between the RH high beam headlamp C1040-1, circuit 1335 (YE/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
No
GO to C3.
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C3 CHECK THE LCM HIGH BEAM OUTPUT CIRCUITS FOR AN OPEN AND A SHORT TO GROUND
- Place the headlamp switch in the OFF position.
- Disconnect: LCM C2145c.
- Measure the resistance between the inoperative high beam 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 C4.
No
REPAIR the circuit in question. TEST the system for normal operation.
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C4 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 Lighting Control Module (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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