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Apr 12, 2012 | 02:23 AM

diablodude64

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Electrical Fun!

I've got an 87 f250 with a 6.9 diesel. I am trying to get the trailer wiring in working order and a few other issues. The trailer wiring is a complete tow harness and I am unsure if it is factory or not, but looks to be. I re-did a few sections as for some reason they melted into one, and so now I have 12v where I should, but I have two wires extra at the back and I am unsure what they go to. One is Red with a light blue stripe if I recall, and the other is black. However, none of the lights work on the trailer still... Any ideas? Where there any fuses to check on an 87?

Also, when I have the headlights on, my left blinker indicator is always lit, but the blinker still works normal. It blinks slower then the right side for some reason though.

What would cause this?

Sorry if this seems all over the place.

Thanks, Kyle

Apr 12, 2012 | 10:58 AM

subford

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From: Easton,Ks

I do not see those wire colors.
Below is from the 88 manual but the 87 should be the same.

Apr 12, 2012 | 11:06 AM

CletusSnow

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From: Bermuda Dunes, CA

If the left blinker is always on with the headlights on, then you still have a short somewhere. Check the bulbs on that side as well, I have seen where someone sticks a single filament bulb in a dual filament socket and had the lights do all kinds of crazy things, If your using your trailer as a test mule, make sure its wiring and bulbs are in order as well.

Apr 12, 2012 | 12:25 PM

diablodude64

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I tested the trailer everything is good. From your schematics, I have all of the wire colors listed and they are already labeled as such. I am down to one wire...

As I understand it this is the setup:

Backup lamps - Black/Pink
Trailer Brake Lamps - Red/Light green
Trailer Ground - White
Trailer Power - Yellow
Electric Brakes - Blue/Black
LH TURN/STOP - Light Green/Orange
RH TURN/STOP - Orange/Light Blue

The "trailer brake lamps" wire is what I am confused at, is that for running lights?

~Kyle

Apr 12, 2012 | 12:54 PM

subford

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Joined: Aug 2005

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From: Easton,Ks

Normally the brake light wire leaving the brake controller goes into the stop lamp switch wire near the stop lamp switch and dose not run to the back of the truck.
I though that was a little strange also.
No it is not for running lights.

Here is the running lights, I think the wire color black should be Brown for the running lights to trailer in the first diagram below: