TROUBLE WITH LIGHTS

JAL51974

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I know this topic has been done many times, and I have already read a bunch of them! Trailer lights none of them are working. So far I did this:
checked for power at vehicle plug (JEEP GRAND CHEROKEE, TOW PACKAGE)- ok
checked main ground at trailer frame and replaced that hardware
checked ground at both side markers and cleaned those up- didn't change any light bulbs for either one
checked ground at both stop/turn/back lights and found one full of water- changed out both sides for LED type

Still no lights anywhere. There is one more light bar on the tail of the trailer and I will check the wiring and ground to that one next. Am I missing something else to check? Is it correct that if one light fixture is broken/shorted out/etc then the whole system does not work- like the Christmas tree lights? I need electric system for dummies!
 

alldodge

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Which connector do you have to the trailer, 4, 5 or 7 blade? Here is the basic wiring using a 4 prong
trailer-lights-wiring.gif
 

JAL51974

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the 4 prong connector and my setup is similar to the one on the right except that the amber lamps are where the clearance lamps are in this pic and there are no side marker lamps near the front of the trailer. It does have the bar of rear marker lights.
 

alldodge

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Turn on 4 way flashers and you should get a pulsing 12V on the Yellow and Green wires. Turn parking lights on and you should get 12V on the Brown wire. Only thing left is White and it should be grounded to the frame. So check these connects on your tow first, then connect to trailer and see what is missing. Use the white wire for all measurements on tow.
 

JAL51974

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AddDodge- I essentially did that to check the tow vehicle connection using the multimeter on the yellow and green wires for the turn signal on and parking lights on to check the Brown wire and all that checked out for the voltage. But on the trailer side of the wiring no lamps light under all conditions- blinker, turn signal, running lights. On the trailer, do all these lamps run in sequence e.g. if the tail lamp is broken then none of the other ones light up too?
 

alldodge

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do all these lamps run in sequence e.g. if the tail lamp is broken then none of the other ones light up too?

No, all lights run in parallel, if one burns out only that light will not work. Sounds to me you do not have a ground on the trailer (the white wire). Is the white wire coming from the trailer side plug welded, or bolted to the frame of the trailer? If yes, then the next, are all of the lights on the trailer bolted to and have a ground connection to the trailer frame?
 

Thalasso

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Most lights ( the bar) only carries the hot (One wire). It grounds itself when bolted to the frame
 

JAL51974

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The white ground wire is bolted to the frame on the trailer side, and I cleaned and used a new bolt for that one as one of the first things I tried to do. I will go back through each of the lamps and check the grounds for each one.
 

Thalasso

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I know this topic has been done many times, and I have already read a bunch of them! Trailer lights none of them are working. So far I did this:
checked for power at vehicle plug (JEEP GRAND CHEROKEE, TOW PACKAGE)- ok
checked main ground at trailer frame and replaced that hardware
checked ground at both side markers and cleaned those up- didn't change any light bulbs for either one
checked ground at both stop/turn/back lights and found one full of water- changed out both sides for LED type

Still no lights anywhere. There is one more light bar on the tail of the trailer and I will check the wiring and ground to that one next. Am I missing something else to check? Is it correct that if one light fixture is broken/shorted out/etc then the whole system does not work- like the Christmas tree lights? I need electric system for dummies!

Did you check for power just past the trailer plug? Highly doubt all the ground connections are bad. You could have it coming out of the tow vehicle but a bad connection on the trailer side
 

JAL51974

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Did you check for power just past the trailer plug? Highly doubt all the ground connections are bad. You could have it coming out of the tow vehicle but a bad connection on the trailer side

No I didn't. How should I check that? I need electrical troubleshooting for dummies I think.
 

Thalasso

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No I didn't. How should I check that? I need electrical troubleshooting for dummies I think.

Take a test light and probe the hot wire from the trailer plug and work your way back. Probably a plug somewhere where the wires are joined together that came apart.

Do you see the little black connection below the cross member. That's a plug connecting the run. It pulls apart

 
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JAL51974

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thanks I will check that hot wire line tomorrow and let you all know what i find. Joe
 

JAL51974

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After about 8 hrs. trying to find the wiring problem I decided to give up today and will rewire the whole trailer on Fri. after work. I learned a bunch of things and thanks to everyone who helped.
Using test light with Jeep lights turned on I tested all of the hot wire from tongue to trailer tail. after fixing two splices that were bad I determined that I had power to all lights by the test light and it was grounded to the trailer ground bolt the whole time. Still no lamps would light, and not turn signals or flasher either. PO did a crappy job of wiring it to begin with- there were so many splices I lost count!
There was power at the Jeep plugin and just behind the trailer plug wires too.
 

airshot

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There does come a time when it is best to just start over....been there, done that. I just went thru a similar thing, 1983 trailer always stored inside but lights were giving me problems for the past 3 years so what the hey. Picked up a complete lighting set with all led lights including side marker lights and wiring harness for 99 bucks. Fed the new harness thru the frame as I pulled the old harness out, mounted the lights and they all plug into the new harness with rubber sealed plugs. Of course I added silicone grease to each plug to be sure connections stays dry and clean. Now everything works great, and leds are really bright. Sometimes you just gotta start over!!
 

JAL51974

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Yeah this way I will only have a few places to splice: each side marker, and one running/stop/signal light at the tail. Much better than before!
 

JAL51974

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Problem with new lights!

From my previous post you know I decided to start fresh and purchased a new wiring harness kit with two LED submersible lights from Harbor Freight. I set up the wire harness and connected the two running red lights correctly. I didn't set up the two side markers yet so it is an unbroken set of wires front to rear of the trailer. However there is still a problem. On the Jeep side I get 11.12 V from the Brown wire connection but once I plug in the harness I only get 0.04 V at the BR wire at the running red lights at the tail of the trailer. Testing the turn signal connection at the Jeep side i get various fluctuating readings when the turn signal is ON and nothing when it is off as it should be. When I checked the red light nothing lights up when all is plugged in and when I turn on either turn signal there is a very faint light. With the Jeep lights on and using a test light grounded at the trailer ground post i get a very faint light when testing on the BR wire of the trailer harness plug. One more test: running 12 v from a battery charger to the BR pole on the trailer harness plug I get a very faint light at the red tail lights and the BR wire at that tail light only reads 3.69 V, the battery charger was grounded to the screw the same as the trailer harness ground.
The Jeep has the round configuration of the factory installed trailer kit, and there is an accessory adaptor that plugs into that and gives me GR plus 3 poles; the trailer wiring harness has GR plus 3 poles attaching to that then splits into GR plus four wires down the trailer, Y, G, two BR wires.

I am thinking that the plug on the trailer harness side is defective, any other ideas?

Joe
 

JAL51974

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NOT SURE, this is the factory installed tow package. Where should I look for that converter?
Some additional information:
With Jeep lights ON using the test light, grounded on the trailer ground bolt, there is only a very faint light on the test bulb when the BR wire is pierced from the harness plug.I also tested the Jeep plug side using an old harness plug with Jeep blinker on- GR and YEL wires tested made the test light blink. turned on the Jeep lights and the BR wire test showed a steady test light so this old plug worked ok and the JEEP SIDE worked ok too.Then I attached an old working red tail light, incandescent bulbs- on license plate side, blinker worked, turn signals worked, but no rear running lights, so no power to BR wire. On the opposite side using the same tail light- no running light, no turn signal, blinker was ok.

finally I cut off the new trailer harness plug and wired in the working old one testing with the LED lights- very weak light for the turn signals, very weak light for the flasher, no running lights.

I have a lot of information but am still confused.
Joe
 

southkogs

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HERE is the fight I had last year. I was a novice at it too ...

Pay particular attention to your grounds. That really messed with me a couple of times.

Also - check on your Jeep: On my RAM 2500, there is a separate fuse for the trailer lights up in a relay center under the hood. I think it was part of a tow package they had on that rig. The dude at the trailer hitch shop had to show it to me. Dunno' if they did the same thing to the Jeeps or not.

What helped me most was Bruce's trick in the thread I linked to use the battery charger as a power supply. That way I could see if the trailer was working right. If it was working, then my problem was on the tow vehicle ... which it was.
 
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