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2003 - 2005 trailer wiring problems


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#1 Torque Monkey

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Posted 11 June 2017 - 08:46 PM

I have been dealing with an intermittent issue with my right stop/turn on my trailer lights. I have already replaced the relays on the PDM board to the 30 amp relays a couple years ago.

02e68c3ac134ff76dcdd3b83f954d1bf.jpg

I figured a relay had gone bad again. One way to tell is if you turn the signal lights on you can hear the relay clicking. If the relay isn't clicking check the fuse first. You may get lucky. The relay uses the fused power for the coil and the power to the lights. So I disassembled it and started testing.

f2c6de55de48b45ec359a2191f946765.jpg

I found a burnt trace for the right turn relay. I fixed that and thought I had it solved. All the relays clicked perfect.

b7c311cdfccfd0f779ce7593890580b5.jpg

The little yellow wire at the bottom is the repair.

0c22d4bba6c0705bc2c7dc100da3f979.jpg

I put it all back together and no luck. Didn't fix the problem. I narrowed it down to the FCM mounted to the side of the PDM. For whatever reason it isn't giving the 0volt signal to activate the relay.

I may have said a bad word or two. That is pretty much a dealer only item and I am pretty sure they have to be flashed. I have replaced it once.


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#2 Torque Monkey

Torque Monkey

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Posted 11 June 2017 - 08:57 PM

So... I was thinking to solder wires in place of the relays and extend them outside the PDM. Since the issue was with the FCM then that idea wouldn't work. I started reading on the interwebz and came up with a Guy that bought a module from Napa that takes the signals from the truck tail lights and converts them for the trailer. Perfect! I went on got one.

b763332cb8c8f3a4ca24ec00a6de3429.jpg

Now, I have been avoiding the wiring under my rear bumper for years. It is a mess and there is a LOT going on under there. So tonight I dove in head first.

9b6e2bce6ae78d9c39a9708ab11e8de1.jpg

Believe it or not, I know what everything in that picture does. I tried to clean it up a bit but it is very difficult without ripping it all out and starting over. I am not ready for that.

5767a702933ec063496b711e9d2493ad.jpg

Again, it isn't pretty but now everything works and it doesn't use the PDM or FCM for the trailer lights. All of the connections were soldered and shrink tubed. It better hold up for a while.


I would very much like to meet the Guy that designed the trailer light set up in the early 3 gens, followed by the Guy that designed the spare tire mount and kick them both square in the nuts!

Shortly I will be installing a fuse block under the hood so I can remove all the wires now attached to my batteries....


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#3 Sasquash

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Posted 11 June 2017 - 10:11 PM

This explains how you knew what wire to wiggle for my backup light and camera to work ! Hahaha

#4 Torque Monkey

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Posted 11 June 2017 - 10:14 PM

This explains how you knew what wire to wiggle for my backup light and camera to work ! Hahaha


Yup!

#5 HOSS

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Posted 12 June 2017 - 04:47 AM

So... I was thinking to solder wires in place of the relays and extend them outside the PDM. Since the issue was with the FCM then that idea wouldn't work. I started reading on the interwebz and came up with a Guy that bought a module from Napa that takes the signals from the truck tail lights and converts them for the trailer. Perfect! I went on got one.

b763332cb8c8f3a4ca24ec00a6de3429.jpg

Now, I have been avoiding the wiring under my rear bumper for years. It is a mess and there is a LOT going on under there. So tonight I dove in head first.

9b6e2bce6ae78d9c39a9708ab11e8de1.jpg

Believe it or not, I know what everything in that picture does. I tried to clean it up a bit but it is very difficult without ripping it all out and starting over. I am not ready for that.

5767a702933ec063496b711e9d2493ad.jpg

Again, it isn't pretty but now everything works and it doesn't use the PDM or FCM for the trailer lights. All of the connections were soldered and shrink tubed. It better hold up for a while.


I would very much like to meet the Guy that designed the trailer light set up in the early 3 gens, followed by the Guy that designed the spare tire mount and kick them both square in the nuts!

Shortly I will be installing a fuse block under the hood so I can remove all the wires now attached to my batteries....


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You missed a spot! LOL 



#6 HOSS

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    I miss you Rob

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    fishing

Posted 12 June 2017 - 04:49 AM

I think my truck lost 10lbs when I cleaned up the wiring under the bumper.

I would like to have a painless wiring box to eliminate the stuff up front but I am afraid to open that can of worms  :help:






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