F 350 2WD Super Duty V10-6.8L (2009)
Refer to Wiring Diagram Set 11, Fuse and Relay Information for schematic and connector information. See: Diagrams/Electrical Diagrams/Diagrams By
Number
Normal Operation
The trailer tow parking lamp relay coil receives voltage through circuit CLS30 (VT/WH) when the vehicle parking lamps are illuminated. The trailer tow
parking lamp relay coil is grounded through circuit GD122 (BK). The Battery Junction Box (BJB) fuse 42 (30A) supplies voltage to the trailer tow
parking lamp relay switch side. When the trailer tow parking lamp relay is energized, the voltage is routed to the trailer tow connector through circuit
CAT17 (BN).
This pinpoint test is intended to diagnose the following:
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Fuse
-
Wiring, terminals or connectors
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Trailer tow connector
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Trailer tow parking lamp relay
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Trailer
PINPOINT TEST AA: THE TRAILER LAMPS ARE INOPERATIVE - TRAILER PARKING LAMPS
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the
connector.
NOTE: Before beginning diagnostics, visually inspect the trailer tow connector mounted on the bumper for signs of corrosion or damage. Repair or
install a new trailer tow connector as required.
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AA1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR
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Place the headlamp switch in the PARKING LAMPS ON position.
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Measure the voltage between the trailer tow connector parking lamp voltage supply pins, circuit CAT17 (BN), component side and ground.
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Is the voltage greater than 10 volts?
Yes
The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
No
GO to AA2.
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AA2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (VEHICLE HARNESS)
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Place the headlamp switch in the OFF position.
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Disconnect: Trailer Tow C4099.
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Place the headlamp switch in the PARKING LAMPS ON position.
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Measure the voltage between the trailer tow C4099-6, circuit CAT17 (BN), harness side and ground.
-
Is the voltage greater than 10 volts?
Yes
