F 550 4WD Super Duty V10-6.8L (2009)
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Disconnect: Trailer Tow C4099.
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Ignition ON.
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Select REVERSE.
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Measure the voltage between the trailer tow C4099-7, circuit CAT03 (GY/BN), harness side and ground.
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Is the voltage greater than 10 volts?
Yes
INSTALL a new trailer tow connector. TEST the system for normal operation.
No
VERIFY the BJB fuse 63 (15A) is OK. If OK, GO to AB3. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
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AB3 CHECK FOR VOLTAGE TO THE BJB FUSE 63 (15A)
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Measure the voltage between the BJB fuse 63 (15A), circuit CLS10 (GY/BN), input side and ground.
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Is the voltage greater than 10 volts?
Yes
REPAIR circuit CAT03 (GY/BN) for an open. TEST the system for normal operation.
No
REPAIR circuit CLS10 (GY/BN) for an open. TEST the system for normal operation.
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Pinpoint Test AC: The Trailer Lamps Are On Continuously
Trailer Lamps
Pinpoint Tests
Pinpoint Test AC: The Trailer Lamps Are On Continuously
Refer to Wiring Diagram Set 95, Trailer/Camper Adapter for schematic and connector information. See: Diagrams/Electrical Diagrams/Diagrams By
Number