Pinpoint Test C: One High Beam Headlamp Is Inoperative
Headlamps
Pinpoint Tests
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 - Expedition
When the SJB detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the HIGH BEAM position, the SJB energizes an internal relay. When the relay is energized, the relay routes voltage through the high beam headlamp voltage supply circuit to the high beams. Ground for the high beams is shared with the low beams.
Navigator
When the SJB detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the HIGH BEAM position, the SJB energizes an internal relay. When the relay is energized, the relay routes voltage through the high beam headlamp voltage supply circuit to the headlamps and the flash-to-pass lamps. A solenoid within each headlamp is energized to activate a shutter which changes the headlamp beam pattern to give the appearance of high beam headlamps. Ground for the solenoid within each headlamp is shared with the low beam circuit. Ground for the flash-to-pass lamps are shared with the front park lamps.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp assembly
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 BEAM OPERATION
- Check the operation of the low beams.
- Do the low beams operate correctly.
Yes
For Expedition, REPAIR circuit CLF08 (YE/VT) for an open. TEST the system for normal operation.
For Navigator, 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 HIGH BEAM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Inoperative Headlamp or Flash-to-Pass Lamp.
- Place the headlamp switch in the HEADLAMPS ON position.
- Place the multifunction switch in the HIGH BEAM position.
- For an inoperative high beam headlamp, measure the voltage between the LH headlamp C1284-7, circuit CLF08 (YE/VT), harness side and ground; or between the RH headlamp C1285-7, circuit CLF08 (YE/VT), harness side and ground.
- For an inoperative flash-to-pass lamp, measure the voltage between the LH flash-to-pass lamp C1549-3, circuit CLF08 (YE/VT), harness side and ground; or between the RH flash-to-pass lamp C1550-3, circuit CLF08 (YE/VT), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
For the headlamp, REPAIR or INSTALL a new headlamp assembly. REFER to Headlamp Assembly Service and Repair. TEST the system for normal operation.
For the flash-to-pass lamp, GO to C3.
No
REPAIR circuit CLF08 (YE/VT) for an open. TEST the system for normal operation.
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C3 CHECK FOR VOLTAGE TO THE FLASH-TO-PASS LAMP USING THE CONNECTOR GROUND
- For an inoperative flash-to-pass lamp, measure the voltage between the LH flash-to-pass lamp C1549-3, circuit CLF08 (YE/VT), harness side and the LH flash-to-pass lamp C1549-1, circuit GD120 (BK/GN), harness side; or between the RH flash-to-pass lamp C1550-3, circuit CLF08 (YE/VT), harness side and the RH flash-to-pass lamp C1550-1, circuit GD123 (BK/GY), harness side.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new bulb holder. TEST the system for normal operation.
No
REPAIR circuit GD120 (BK/GN) (LH flash-to-pass) or circuit GD123 (BK/GY) (RH flash-to-pass) for an open. TEST the system for normal operation.
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