Trailering Light Issue With 99 Silverado

[99silverado1500]

On my 99 Silverado, I have an adapter to go from the 7 round to go to the 4 flat on my boat trailer. I did a new ground today, and replaced the brake bulbs on the trailer as they were shattered from me forgetting to unplug when I launched it first thing this season. Anyways, I replaced the sidemarker rear lights and the rear brake/running lights today. Now when im driving with no headlights on, the cluster and the radio lights dim when I hit the brakes. The wierd thing is it didnt do it about 3 out of 20 brakes so im thinking its a short issue or somethings messed up. I didnt change any wiring other then lengthening the ground and its a clean tight ground and the solder joints are solid. The lights do not dim when the headlights are on but only when they are off. The battery gauge goes below 14 when I hit the brakes but goes ab ove when i let off. I replaced with exact replacement bulbs so they are not high output they are what came with the trailer.

[c4cruiser]

I would inspect all of the wiring on the trailer as it sounds like a short to ground issue given the voltage drop. It could be that a wire may be rubbing on metal somewhere or the brake/turn wire is shorting to the ground wire in the harness.

 

It might be a good idea just to buy a new harness and re-wire the trailer seeing as how you have replaced some lamp housings. Also, just make sure that when you connected the new housings, you didn't connect a lamp lead to a ground wire in error.

[99silverado1500]

The problem turned out to be the rear bulbs not being turned in all the way and shorting across and making the side markers come on from the feedback from the short. Its all fine now, at least at the moment.