Trailer Wiring
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Joined: Oct 2008
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From: ON & AB, Canada
Trailer Wiring
Question regarding 2 trailer circuits.
97 F359, factory trailer wiring harness. I bought he pigtail to connect the brake controller and brakes work, as do brake and running lights, right and left flasher. sofar so good.
This leaves 2 circuits on the 7 pole connector......Auxillary and trailer power.
1 - Trailer power (battery charge, top right connector on the truck plug) has a 30 AMP maxi fuse oin the power distribution box. The fuse is good and has power. But I get nothing at the plug. Its the orange wire on the factory harness. Any idea where I should start?
2 - Auxilary connector. Again its factory prewired and connected to the trailer plug. Since it is an optional circuit I assume that Ford did not connect it to an existing circuit. Or did they? Anyone know where this wire terminates?
97 F359, factory trailer wiring harness. I bought he pigtail to connect the brake controller and brakes work, as do brake and running lights, right and left flasher. sofar so good.
This leaves 2 circuits on the 7 pole connector......Auxillary and trailer power.
1 - Trailer power (battery charge, top right connector on the truck plug) has a 30 AMP maxi fuse oin the power distribution box. The fuse is good and has power. But I get nothing at the plug. Its the orange wire on the factory harness. Any idea where I should start?
2 - Auxilary connector. Again its factory prewired and connected to the trailer plug. Since it is an optional circuit I assume that Ford did not connect it to an existing circuit. Or did they? Anyone know where this wire terminates?
Tuned
Joined: Jun 2004
Posts: 472
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From: Goodyear, AZ
1 Is the truck running when you test for the trailer power, the truck has a relay and doesn't give power to that circuit if the truck is not running.
2 - the auxilary circuit should be for the reverse lights if I remember right
2 - the auxilary circuit should be for the reverse lights if I remember right
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Joined: Jan 2007
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From: Whitewright, Tx
What he said is correct.
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From: ON & AB, Canada
1 - yes, truck was running. yet no power on the battery charge circuit.
2 - So you think that when the truck reverse lights are on, the trailer backup lights should be energized?
2 - So you think that when the truck reverse lights are on, the trailer backup lights should be energized?
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From: North East Ohio
Try disconnecting the plug at the harness under the bed, and test there. Maybe that connection/plug is bad. Otherwise the only other plug is up near the firewall if I recall correctly, try there. If nothing still, then ???
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
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Joined: Sep 2007
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From: Medford Oregon
x2 .. both circuits require separate relays. Are they there ?
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From: ON & AB, Canada
yes, all relays are in place.
Connectors at the bumper are good. I'll trace it forward and check them in the morning.
Connectors at the bumper are good. I'll trace it forward and check them in the morning.
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Elder User
Joined: Oct 2004
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From: Olympia, WA
When I bought my rig the trailer plug had a couple dead circuits. I back traced the harness from the plug forward and found that the 12V charge wire and backup light wire were not connected to the plug. It did not look like a "custom" repair, looked pretty factory to me the way it was secured. Not sure why they weren't connected, but once fixed everything works as it should.
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From: ON & AB, Canada
Thx karl.
Thats what I suspected, as the center, backup light, is really an auxiliary circuit as far as the 7 pole standard goes.
I meant to chck the truck but haven't had a chance yet.
Thats what I suspected, as the center, backup light, is really an auxiliary circuit as far as the 7 pole standard goes.
I meant to chck the truck but haven't had a chance yet.
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