Trailer Wiring Problem...

[TBigLug]

I need some help with this one. I have a 18 ft. stock trailer w/ a 6 pin round connector. When I plug it into my truck, turn on the parking lights, the PL will work until I hit my brakes. Then they go dark, no PL or BL. Happened once with my Grandpa's truck, we just shook the connector a couple times and started working. Any ideas? Also, when I first plug in the trailer my brake controller lights up and trailer brakes go on. If I shut off the truck and restart, it goes back to the original problem. Help...

 

[tonkadoctor]

Sounds like a loose or broken wire inside the trailer plug or a short somewhere on the trailer or possibly the truck too. In my experience I've found the trailer to be at fault 99% of the time.

6 pin connectors are usually pretty easy to open and check or if you have a meter start testing the terminals for continuity.

IIRC the center pin is ground

On the trailer check continuity as follows

• Put on probe on the center pin and check for continuity with all 5 outer pins you should have continuity on the pins for the park lamps, brake lamps and turn signals.....Not sure on the electric brakes, somebody will have to refresh my memory on this one.
• Place probe on one outer pin and test for continuity with the 4 remaining outer pins ....There should be none, if there is you have a short bewteen thos 2 wires
• Repeat the last test with the 4 remaining pins

You can check the truck connector the same way but in the 1st test you should NOT have any continuity with any of the pins the rest is the same as the trailer.

Testing like this will only take about 10 minutes and that's where I'd start.

 

[MT.EZ]

Most 6 pin plugs are labeled as to what function the pin has. The center pin is labeled ACC and the five around the out side are GD= Ground, S= stop, RT= Right Turn, LT= Left Turn, T/M= Tail Markers. Depending how your truck and trailer are wired, most people put the brakes in the center instead of the one marked S.

 

[cjensen91910]

Here is a link to a pge that gives a pretty good drawing of a six pin. This site has a seven pin drawing and table also. Hope this helps.

http://www.marksrv.com/6way.htm

 

[Crumm]

Sounds like a bad ground to me. Check the connections in both plugs, clean the plug contacts and check for a good ground on both the trailer and tow vehicle.