Trailer wiring - stumped

[LIL EVO]

So everything was working fine and then my trailer running lights are no longer working.

7 pin connector on both ends. Trailer brakes, left turn, right turn, and brake lights all work. Running lights on trailer do not.

The running lights on the truck work and both running lights on the trailer work if I remove them from the trailer and hook them up to a battery.

There is 12+ at the "tail" pin on the truck side. When I plug in the trailer though, there is no voltage on either the truck "tail" pin or the trailer "tail" pin.

I also bypassed the tail light converter with no luck.

So when I plug in the trailer, I lose the 12+ on that brown wire. (truck running lights stay on no matter what)

Any ideas what the problem is?

It's not a ground because I made sure all grounds are solid and tight. The winch also works through the ground wires (even with the trailer not attached to the receiver)

[DocDave]

How old are the 7-Pin connectors you are dealing with? They may be corroded. I have seen some that look fine to the naked eye but do not conduct enough electricity to light the bulbs.

[LIL EVO]

I traced the problem back to a vampire clip, in between the truck taillight housing and the tail light converter. What threw me off it that I was still getting 12V on both sides of the wire.

Thanks!

[fly5150]

check that the pin isn't bent a little. I have had the pins almost touch, but not make good contact.

[97z2801ss]

just read your story of the lil evo group, good read man!

[indyzmike]

I traced the problem back to a vampire clip, in between the truck taillight housing and the tail light converter. What threw me off it that I was still getting 12V on both sides of the wire.


You were probably checking for voltage with a digital meter. A digital meter only puts a tiny load on the source. The bad connection was good enough for the meter to read voltage ,but not good enough to power the lights. A test light, using an incandescent bulb, works the best for some troubleshooting. Checking for voltage with the lights plugged in works good too.

Digital meters are very sensitive and can give voltage readings like this. The meter is not wrong, it is reading correctly given the circumstance. Mike

[BadAzzGTA89]

I traced the problem back to a vampire clip, in between the truck taillight housing and the tail light converter. What threw me off it that I was still getting 12V on both sides of the wire.

Thanks!

If this is what your talking about http://www.ideaphile.com/bmw/mods/v1/power-clip.jpg
Those are junk! Sealed butt connectors or nothing.

[DocDave]

If this is what your talking about http://www.ideaphile.com/bmw/mods/v1/power-clip.jpg
Those are junk! Sealed butt connectors or nothing.

I second that. DO NOT USE THOSE! They rot out and then fail; if the load on them is high enough they can even cause melting of the surrounding wires or even a small fire. Solder and heat shrink if you can, otherwise use a sealed but connector as BadAzzGTA89 suggested.

[LIL EVO]

Yep, I will be. They must've been on ever since the hitch was installed 12 years ago.

[lordairgtar]

Yeah, those vampire clips are well named...they suck! They are just meant to be cheap quick down and dirty installs. Crimped butt splices and soldering are the best.