trailer wiring

[crispyboy]

Last weekend I hooked up my rig with trailer wiring.
Everything went ok except that when I use my brake lights with the trailer hooked up both the vehicle brake lights and trailer lights are dim.
When I check voltage at connector under rear fender I am at 10 volts. I only get 8 volts at the trailer connector.
I double checked all grounds and reworked connection two times.
Anybody else ever have this problem?

[reddog]

What year FSJ? The later years (not sure the cutoff but I think late 70s and up Cherokees and 84 and up Wags) have a separate brake/tail lights and need an converter to go from 5 wire on the truck to the 4 wire trailer. What setup do you have?

Kerry

[crispyboy]

86 truck
wiring on truck under each fender:
yellow - running light
orange - right turn signal/brake
black - ground
green - left turn signal/brake

[Woody Mammoth]

Last weekend I hooked up my rig with trailer wiring.
Did you hook up the trailer connector directly or via a converter module?

On my 91 Grand Wagoneer, I used Chrysler converter module and works fine except turn signals were week. So I have to get a heavy duty turn signal flashers.

[crispyboy]

I hooked the wiring up directly. I am not familiar with the converter. Could you explain?
BTW my turn signals are very bright.

[Coley]

How opportune that this came up now, as I'm dealing with trailer wiring, too. I have the BIG 5 plug connector.

I ordered a 5-way flat to a 4-way flat adapter from this outfit. Hope it works.
http://www.bageco.com/adapter.htm

[Woody Mammoth]

As reddog mentioned above, some car or truck has more wires to accomplish all the lighting funtions, yet jamed all the functions into 4 wire trailer connector. Tail light converter will make everyting happy happy if directions is followed. I guess it also eliminates parallel or serial wiring of two of the same function lamps, hence dim lights or reduced voltage. On late model car and trucks, all they need is a T-connector that fits into their factory wiring harness, but no such luck for our beasts.

Follow the link below for better explaination than I can write.
http://www.drawtite-hitches.com/electrical/modulite.htm

http://www.draw-tite.com/

U-Haul, Walmart, and most autopart stores carries these coverters.

[Ed Jack]

I'm in a similar situation. I took my 88GW to uhaul. They have a very nice flat4 plug with indicator lights on it, makes troubleshooting much simpler. They did the install with the module for $40, when you consider that most places charge $25 for just the module, this isn't that bad at all.

HOWEVER, when I hook up my trailer I get very low voltage to the lights, 10v or so. And eventually I blew the 15Amp fuse under the dash for the turn signals and reverse lights.

So, I need to track down the cause of the blown fuse.

Has anyone experienced this? Has anyone solved this problem on their vehicle?

My plan currently is to run a temporary 12v back to the lights, bypassing the original wiring, and see if that increases the voltage. Also I plan to check the lights on the wagon, see if there's a poor ground, or high resistance on a particular bulb (probably try taking out bulbs and watching the effects)

Any suggestions are welcome.