Trailer wiring problem
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Freshman User
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Trailer wiring problem
I hooked a trailer to my truck's factory trailer connector and the brake and driving lights worked but the turn signals(left and right) did not. So I started tracing out the wires into the rear connector at which they work there. I noticed that the wires are different colors which appear they run back to the cab. So is there a fuse up under the hood for the trailer connector that maybe blown? The tail lights in the bed corners work fine.
Junior User
Joined: Dec 2007
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From: D'Hanis, TX
If I read you correctly, you have working voltages at the trailer connector for your turn indicators (as determine with a test lamp/voltmeter). If that is the case, then you need to check that the pins on the truck connector match to those on the trailer plug. If they do, then you have problems on the trailer side.
An easy way to test is to open the junction box on the trailer and put the test lamp there. Obviously, you have to test left & right seperately.
Bob
An easy way to test is to open the junction box on the trailer and put the test lamp there. Obviously, you have to test left & right seperately.
Bob
Posting Guru
Joined: Aug 2008
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From: No.Va.
There are two trailer turn relays under the hood.
They are fine since you have turn signals at the rear of the plug.
Check the outside of the plug (where you plug the trailer into),do you have voltage there?
If not,the wiring at the back of the truck plug is bad.
(ford has a repair kit for this.)
If you have voltage at the plug end where the trailer connects,then it is a wiring problem w/ the trailer.
They are fine since you have turn signals at the rear of the plug.
Check the outside of the plug (where you plug the trailer into),do you have voltage there?
If not,the wiring at the back of the truck plug is bad.
(ford has a repair kit for this.)
If you have voltage at the plug end where the trailer connects,then it is a wiring problem w/ the trailer.
Senior User
Joined: Feb 2009
Posts: 415
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From: Long Island - NY
I had a similar problem, except it was the other way around -- My turn signals worked on the trailer, but not the running lights. It ended up being a bad relay under the hood. I swapped it out with the windshield power washer relay and tested -- worked fine then .... Good luck
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I do not have voltage at the trailer connector at the back of the truck, but the turn signals work on the bed of the truck. What confuses me is that I even jabbed my tester into the wires that are directly coming out of the wiring harness right and I do not have voltage. I do have voltage at the trailer connector fo the brake lights and driving lights.
Which relays under the hood are they? For I do not have a owner's manual.
Which relays under the hood are they? For I do not have a owner's manual.
Posting Guru
Joined: Aug 2008
Posts: 1,845
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From: No.Va.
Look here for relay info.
https://www.ford-trucks.com/forums/8...-f250-psd.html
First check fuse for trailer tow relays = 2.6 .(under hood)
https://www.ford-trucks.com/forums/8...-f250-psd.html
First check fuse for trailer tow relays = 2.6 .(under hood)
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Joined: Dec 2007
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From: D'Hanis, TX
Last year I had a similar problem, except mine was the running lights on the trailer. In my 2000 SD 7.3L 4x4, there are relays that control the voltage to the trailer. In my case I traced voltage OUT of the control relay but it didn't get to the trailer connector. After much work, I discovered a connector near the bed of the truck about 1-1/2 foot (wire length) from the trailer connector. I pulled it apart and I had voltage that far. The contacts of the connector were a bit 'dirty', so I cleaned them and put the connector back. Then I had working runing lights. This connector is in a location that dirt and water can splash up on it. You might want to check it out. Just another suggestion.
If you don't have voltage at that connector, then the relay suggestions are a good place to start.
Bob
If you don't have voltage at that connector, then the relay suggestions are a good place to start.
Bob
