Wiring schematic for trailer/towing circuits

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Apr 1, 2009 | 12:06 AM

greatmej

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Wiring schematic for trailer/towing circuits

I recently towed for the first time in a while last Saturday. After unhooking the trailer, my parking lights remained on and the only way I can get them off is to remove the #4 fuse under the hood or disconnect the battery. When I reconnect the battery or reinstall fuse #4 the parking lights stay off until I turn the lights back on at the switch. To turn the lights back off I have to pull the fuse again. Currently I'm running without fuse #4 and the lights are working as they should but I'd like to diagnose the issue and correct it. It seems as if there is a bad relay down current from the fuse, if it was just a short or ground wouldn't the parking lights come back on when I reconnect battery power via cable or fuse? Does anyone know what relay (if there is a relay) the #4 fuse powers on its way back to the trailer plug? Even better the wiring schematic and factory location of a potential relay? I pulled the factory trailer tow relay's under the hood with neither affecting the parking lights. My truck is a 1999.5. Thanks.

Apr 1, 2009 | 09:00 AM

danskool

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From: Buffalo, NY

I am at work right now and can't look through the wiring schematics to closely. But wire3,wire5 and wire6 schematics reference #4 and relays.
The schematics are in this zip file. http://www.geocities.com/dirtsplat/WireSch.zip

Apr 2, 2009 | 11:30 PM

greatmej

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Thank you for the schematics. I'm out of town with work, but in reviewing the documents I think it may be the trailer running lamp relay. Can you tell me where that would be located on a 1999?

Apr 13, 2009 | 05:16 AM

danskool

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From: Buffalo, NY

Fuse #8 15amp
Trailer Tow Electronic Brake Illumination,
Park Lamps, Trailer Tow Park Lamp
Relay Coil

I see this in my book. But don't see were the relay is located.

Did you find it?

Apr 14, 2009 | 10:15 AM

greatmej

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Dan,

Work hasn't allowed me to isolate the relay yet. I pulled the #4 from under the hood which allows me to turn the lights off with the switch in the mean time. Hopefully I can start tracing the circuit this weekend.