Ford Workshop Service and Repair Manuals

Yes

The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.

No

For the 4-pin connector, GO to AA3.

For the 7-pin connector, GO to AA2.

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AA2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (7-PIN)

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Disconnect: Trailer Tow C439a.

-

Measure the voltage between the trailer tow C439a-6, circuit CAT17 (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

GO to AA3.

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AA3 CHECK THE TRAILER TOW PARKING LAMP RELAY

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Place the headlamp switch in the OFF position.

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Disconnect: Trailer Tow Parking Lamp Relay.

-

Substitute a known good relay.

-

Place the headlamp switch in the PARKING LAMPS ON position.

-

For the 4-pin connector, measure the voltage between the trailer tow C439b-3, circuit CAT17 (BN), harness side and ground.

-

For the 7-pin connector, measure the voltage between the trailer tow C439a-6, circuit CAT17 (BN), harness side and ground.

-

Is the trailer tow parking lamp relay OK?

Yes

REMOVE the known good relay. GO to AA4.