Trailer Wiring Help!!!!

[skankbutta]

Hi guys. I am having some issues with wiring my trailer. The problem has to be on the car end, because I tested it on another trailer and the same issue happens.

 

A little background first:

 

I drive an 07' Jeep Compass. I am using this wire harness kit : http://www.towready.com/pdf/N118428.pdf

The trailer lights are all new, along with all the wires on car and trailer side.

 

 

Now my problem is that the right trailer light, regardless of the trailer (tried my boat trailer and a utility trailer), stays on. It even stays on with the Jeep off if I have the 4-flat connectors connected. If I turn on the right signal, nothing happens because the light is on. The left side works perfectly. All of the jeep lights are functioning normally.

 

Anyone have any ideas what could be causing this?

[dagoat_1]

If light is on with the jeep turned off then it sounds like you have accidently connected it to a constant 12v supply line. Double check your harness.

[wallyboss]

First thing to make sure is that you have a good ground. You can try a temporary one

[skankbutta]

This harness is run through a 10 Amp fuse, which is connected through the car battery for powering the lights (called ModuLite®).

[Fisherman]

If you have followed the instructions and both trailers are doing that, then it may be a bad ground from trailer to jeep or possibly the black box is defective. Don't use the trailer hitch as a ground(not questioning your ability here), some try to do it with bad results. For testing, run a real ground wire from the base mounting bolts on one of the trailer lights to a clean ground point on the jeep, (not the hitch), maybe one of the screws for the light assembly.

[skankbutta]

These are my grounds right now.

 

For the Jeep side, I drilled a hole into the Jeep frame and sanded it down to the metal. I then attached the ground wire to the frame with the supplied screw.

 

For the trailer side, I have the ground wire coming off of the 4-wire connector going to a screw, which is in the trailer body. The two trailer lights are each ground to their mounting screws.

 

I'll try a few configurations tomorrow after work. I'm thinking it might be a ground issue as well.

 

Thanks for all your help so far. If anyone else has anything to add, please don't hesitate.

[Dara]

A bad ground stops you from getting power to the lights. It doesn't give you extra. As was said above, you have connected one wire to power. Figure out which one with a tester. Then disconnect it and put it in the right place.

And why do you have to connect to the battery? Sounds like that is where the power is coming from

[MillerPhoto]

Faulty box.. Seen it before.. Considering I have installed over 300 of them.... on average one out of every 25 boxes are faulty or will fail with in the first year.

Thats the problem with mass computer controlled assembly.. Parts start to wear and specs start to shift and the manufacturer doesn't compensate for the wearing

parts.. Even 1/100th of a inch can mean the differnce between working and not working.

 

Also to get a test just on the jeep itself.. use a test light, connect it to the frame or the exhaust tail pipe, and probe the car end of the connector while having someone else

control the brake lights and such, test it that way to see your results. on the flat four plug your wires are always...

 

Brown - Tail

Yellow - Left

Green - Right

White - Ground

 

There is also the possibility that the t-connector on the right side was pinned wrong.. Found that a few times also.. go back to where you bought the kit, and get them to open a new package for you and remove your light and compare the connector pin for pin for each wire to make sure they were installed at factory correct.

Edited June 17, 2009 by Miller Photo

[Fisherman]

And why do you have to connect to the battery? Sounds like that is where the power is coming from

Read the first post again and check the link, it's a module that goes in series with the vehicle/trailer wiring.

12V power must be supplied from the battery to activate the module so that the computer for the vehicle lighting doesn't sense added power draw and shut down.

[Dara]

Read the first post again and check the link, it's a module that goes in series with the vehicle/trailer wiring.

12V power must be supplied from the battery to activate the module so that the computer for the vehicle lighting doesn't sense added power draw and shut down.

 

 

I didn't read it that close. Any vehicle I wired from scratch was old, and any new ones I have were already wired, or you just bought a harness that plugged right into the vehicles wiring.

 

Gotta love puters

[MillerPhoto]

The reason for the power to the module is that the vehicles use a negative wire system.

There is full time power supplied to the light, and when you hit your brakes or turn signals its grounded.

They swtiched to that system due to the fact they were able to eliminated full time live wires under the dash.

[skankbutta]

Okay, tried a few combinations and still the same issues. After a little more investigation, I have determined the problem is between the ground and the green wire.

 

If I remove the ground from the Jeep, the light that stays on will shut off and none of the other lights will work.

 

If I go to the right trailer light and disconnect the green wires of the harness and right trailer light, then the light goes out, but the left trailer light still works. If I touch the green wire from the harness to the brown wire of the right light, the right light will light up (It's dimmer than with wires attached normally.) If I remove the ground from the right light the light is still receiving power because it is on (extremely dim, but on).

 

Also, with the 4 connectors connected and all my grounds in place but the jeep side, if I touch the white ground wire to the jeep frame it sparks. Similarly, if I have everything in place, but the ground coming off of the trailer 4-plug connector and touch it to the trailer frame, it sparks.

 

Is it a bad ground on the jeep side?

 

I'm going to contact the place I bought it from and see what's the deal.

 

Thanks for any other suggections.

[Fisherman]

Okay, tried a few combinations and still the same issues. After a little more investigation, I have determined the problem is between the ground and the green wire.

 

1. If I remove the ground from the Jeep, the light that stays on will shut off and none of the other lights will work.

 

2. If I go to the right trailer light and disconnect the green wires of the harness and right trailer light, then the light goes out, but the left trailer light still works. 3. If I touch the green wire from the harness to the brown wire of the right light, the right light will light up (It's dimmer than with wires attached normally.) 4. If I remove the ground from the right light the light is still receiving power because it is on (extremely dim, but on).

 

5. Also, with the 4 connectors connected and all my grounds in place but the jeep side, if I touch the white ground wire to the jeep frame it sparks. Similarly, if I have everything in place, but the ground coming off of the trailer 4-plug connector and touch it to the trailer frame, it sparks.

 

Is it a bad ground on the jeep side?

 

I'm going to contact the place I bought it from and see what's the deal.

 

Thanks for any other suggections.

 

1. That white ground wire is needed for the module system..suspicion..module is bad.

 

2. Disconnecting the green, disables the right trailer brake/signal..normal.

 

3. Green wire is now receiving power from the park light wire..normal.

 

4. Removing the ground, it should go out, but most likely grounding back through one of the other lights.

 

5. Not knowing the inner workings of the module, I still don't think the white wire(Jeep side) should spark.

 

How about trying this test: If you have a spare 12 volt battery, check each trailer light individually.

On the 4 Flat trailer connector, 12V - to the white, 12 + to the green, yellow and brown, one at a time. See that each light functions brightly, green and yellow will be bright, brown(park) will be a bit more dim, it's normal. If you have extra clearance lamps(yellow at front, red at rear middle) they will also light with the brown. The yellow and green are stop/signal but of course won't flash, there's no flasher in this test. If these all work, no exceptions, then the trailer is okay.

 

Now take a 12V test light or a voltmeter set to 12V DC or higher. Black probe to the white ground tip on the Jeep 4 flat plug, red probe to the brown, should get +12(maybe a bit higher), red probe to yellow, have someone step on brake pedal, +12, do same for green, +12V. Now turn on your left signal on the jeep, ignition on, again check both the yellow and green wires, the test light will flash or your voltmeter will jump to +12V intermittent. Let us know. I'm still leaning a bit to a bad module.

 

Brain poot..one more thing, with the Jeep ignition off, test for +12V between the white and green at the 4 flat Jeep plug. You should not be getting anything.

Edited June 18, 2009 by Fisherman

[fishboy]

I had a similar problem with a Windstar except it ended up twice with only the right signal working. They also use that electrical system (low side switching) where a computer module grounds the appropriate lamp circuit rather than the traditional way of providing power when needed. The problem is that you can't just splice into the wiring old-school style and need to run a separate circuit with a module for the trailer too. The aftermarket ones in my experience weren't reliable and I eventuall sucked it up and bought the trailer wiring harness from the dealership as they're all wired to that point in the factory. It solved my problems and I agree with fisherman that it's the aftermarket black box.

[skankbutta]

Definitely the back box. If I use a test light on the 4-wire plug from the jeep, even with it turned off, it produces power. I touched the ground to the white wire and the light to the green (Light). I touch the ground to the green and the light to the white (Light). It seems like the ground and green have become the same wire. I've blown 2 fuses so far with this harness.

 

I'm going to contact the place I bought it from and see what they say.

 

I just might end up contacting Chrysler and getting the one they offer.

 

Thanks for all your help guys. It's appreciated.

[Fisherman]

Let us know how it turns out when you get a new module, might help the next guy out.