trailer light problem - help !!!

[sbiel]

I am looking for some expertise in fixing my trailer lighting problem. It's only related to my truck (98. 5 quad cab, swb, 5 speed, factory trailer package) - no trailer plugged in at this time. Sorry in advance for the long post . .



The running lights and power plug on the rear bumper outlet do not provide any power. The blinker lights work fine.



Looking under the hood the 40 amp fuse was blown. Replaced it, with no change. Took a voltage meter to the hot power line for the fuse and it show 12 volts. Went to the other side and it's reading 12 volts !! Why have a fuse ???



Further investigation shows that if I pull the brake controller plug (sorry, forgot the vendor) from the truck's wiring, the 'other side' voltage goes away.



I tried swapping the relay with another, and nothing changed ...



If I disconnect the the trailer brake controller, I get 0. 9 volts to the stop / turn signals. Remove the fuse and I get 2. 4 volts. Remove the fuse and relay and I get 2. 1 volts.



Thus, I am confused ... It looks like a intermittent / random problem ... I'd appreciate ideas on how to test the relay and any other ideas that I might want to look at. I checked the rear trailer connections and all looks good. Do not see any striped / nicked wires, but I've missed things before.



Many thanks in advance !!!



steve biel

-- email address removed --

 

[DarrellB]

Sbiel, Thats a good one you sertainly stumped me. I have a friend with a 99 gasser and he had his backup lights stay on one night when he shut off the truck. He gave me a call at work and I told him to just disconect the batteries. The next morning he took it to the dealer and they had to replace the hole trailer plug, wiring and all. Brian said it was all melted together(the wiring that is). the dealer told him that they had seen it in about half a dozen trucks all 2500 4x4s. Might want to take a look at the wiring running to the plug.



Good luck

Big D

 

[PHaller]

I had a similar problem with my 97. It turned out to be corosion bridges inside the trailer tow receptical. I took it all apart and cleaned the contacts and wires and reasembled using di- electric grease. Problem solved.

-Paul R. Haller-

 

[merryman]

Electricity=witchcraft; don't go near the stuff.



Vaughn

 

[Rambling]

Yep! Another long one.

Steve,



After you replaced the fuse you measured 12 volts on both sides. What that might mean is that somewhere after the fuse there is an open/high resistance or you have a wiring error and the controller is applying 12 volts to the other side of the fuse.



It's also possible the fuse is blown again. Especially since the voltage after the fuse disappears when you disconnect the controller. If the fuse were good, you should read 12 volts before and after the fuse when you removed the controller plug.



I know my controller's wire color code didn't match the Dodge color code. It is important to match signals rather than colors. Wierd and bad things can happen when the signals are mixed up. Including damaging the controller.



Hope some of this makes sense and your problem turns out to be a just a little one. Email me if need be.

 

[sbiel]

trailer lights

Hi all ...



thanks for the comments ...



I cleaned up the connections and without the trailer controller (TC) plugged in, everything seems to be normal. The TC was installed several years ago, and has done fine so far.



with the TC plugged in, the fuse plugs are both hot. remove the TC, and only one side is hot.



with the TC plugged in, the trailer power plug is hot (normal situation). however the brake plug is always hot.



thus, I think that the TC is the problem. I am gonna talk to the folks who installed it regarding testing it, warranty, etc.



again, many thanks !!!



steve

 

[sbiel]

I talked with the guys at the shop and we tested it. all is okay.



I guess that I had to cleanup the connections and replace the fuse.



apparently, it's normal for the TC to provide power to the fuse box. strange ...



thanks for the advice !!



steve