TOPIC: trailer light woes ...

I have almost successfully wired a 98 Isuzu Rodeo to my old trailer. The only light that does not work is the passenger side tail light. It will not light up when I turn the headlights on. However, the break and the signal light both work on that side. The other side works normal. I picked up some new bulbs and one of those little tester light things. Could it be a bad ground?

Nope, if the stop/turn works you've got ground. Probably a broken wire or bad connection between the two tail lights. (Often they feed from one to the other for the "running lights".)

It can always be a bad ground. First make sure your tow vehicle works with that tester you bought. That's easy to eliminate, as long as it works.

If the tow vehicle lights work, it's the trailer. Like Mark says, it is not unusual for lines from one side (particularly tail) to be spliced from or to the other side. Personally, to avoid aggravating ground problems, I have got in the habit of running a white ground wire to every light.

Keep us posted on how you make out.

Frank

another trick is to use a car battery and some small wire leads and test things without the trailer being hooked to the car. ground the neg on the bat to the trailer, then stick the hot lead into each plug hole. this way you can see the bulbs being lit by each wire.

if both filaments are in the same bulb (1157) then it should be the same ground. it would have to be in the pos lead going to the light. BUT stranger things have happened.

if it drives you crazy too long, a trailer light kit is only $20-$30

Good points as well HopFrog. It doesn't take much juice, a lawnmower battery will work. (I've done that for testing too, didn't even think about mentioning it.)

And of course Frank is spot on about the ground, it's one of the most frequent causes of light malfunctions IMO.

Bad grounds, bad connections, severely corroded wire where the insulation has been compromised (sometimes hidden up under the frame!) can be very elusive and frustrating. A complete trailer side harness replacement only cost me around $15 for my Holsclaw, then your worries are over!

Good luck with it, let us know how you come out.

Something else I forgot to add that brings trailer light success is Liquid Electrical Tape. Used correctly, you will never have to worry about a corroding connection again! I've been a fan for twenty years now, and use it so regularly I forget other people don't know about it...

Frank

I always put a few dabs of dielectric grease on my plugs. Last forever.

awesome! good stuff guys. thanks a lot. now i just need to figure out what i am going to do with the motor that doesn't work anymore.