plumsal

Had to replace the trailer side 5-way flat. Cut-off at the end and attached a new one, matching up all colored wires. Did a neat job and used electrical tape to seal each splice.

But only the side lights work. No brake lights, no blinkers, etc.

Using a Jeep Cherokee with a pre-installed 7-way blade connector. Use a 7-way blade to flat adapter.

Did I screw-up somehow? Bad ground? How do I check?

Any help appreciated!

aero993

I would use a light pen or a dmm (digital multi meter) to check that everything is working come from the truck. I once rewired a trailer when the problem was with the truck.
Have someone hit the brakes and check that. Have someone hit each turn signal and check them. Lastly check the running light.

Hawkeye

Sounds like a ground problem. Check the ground at both the trailer and truck. Did they work b4?

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Hawkeye

SHAMROCK69

You need to get a voltmeter and test each lead at the tow vehicle and work back wards. I doubt it is a ground issue as the running lights and brakes/turn signals share a ground. If all leads at truck have 12 volts then move back to turn signal lights and see if you have 12 volts there. You can also use your voltmeter to check ground.

Hawkeye

I was thinking if the ground is weak it only has enough potintial to ground a light or 2. Also not sure if his set up is using the trailer frame localy at each ground or is it tied into a common wire for all the lights. If its the later it could of corroded thru the ground wire between the side lights and the rear light.I cant tell you how many times bad grounds are the problem on boat trailers.

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Hawkeye

SHAMROCK69

Valid point and why I prefer using a voltmeter over test light as will show a voltage drop and a poor ground can come up as low voltage. Every time I have tried to fuss with trailer lights without a voltmeter or test light it has taken longer and usually resulted in me having to eventually pull one out.

plumsal

Thanks for the replies - I will try cleaning all connections first, especially on the vehicle side. The trailer is brand new (but the connector was dragged and damaged). I will check with a test light first to see if anything obvious. The truck-side blade connector looks like crap.

dward51

I recently replaced my rear tail lights with LED's after someone clipped one at the local ramp and broke it. I also decided to change out my plug from a 4 way to a 7 way to match my truck setup so I would not have to use an adaptor.

When I first wired it up and plugged it into the truck to test the lighs, I found similar problems to what you reported to have. I found the 7 way plug & cord I ordered off e-bay did not match the normal color code for trailer wiring. It was all jacked up. I finally had to take a multi-meter, plug in the cord to the truck and verify the real color code. Once I knew the real color code for that particular combo and rewired it, it works perfectly. I do remember the brown was not the tail light line but was actualy one of the turn signal lights. That was really wacked.

So depending on where your plug/cord came from it may have similar issues. Of course my e-bay special was made in China.