I have a 1983 E-350 cube truck that I am having problems with, mainly with the rear running/brake/signal lights.

When I turn on the switch for the running lights, both rear lights illuminate, with the right one being much brighter (almost as if the brakes were applied). My initial guess is that the two leads going into the lamp assembly might be reversed. Not sure.

Next, when I push down the brake peddle, neither light seems to get any brighter (but like I said the rear right light might have the wires reversed). The left lamp does not change in brightness.

Finally, neither light responds to the turn signal switch.

The lights worked fine when I bought the truck in February. I'm not sure why this changed...

The wiring leading to each of the lights looks pretty solid, with fairly clean wire splices. I don't see any grounding problems either. I traced the wire harness the length of the body to the firewall and haven't found any problems. The four way and turn-signal relays work (as the front running lights/blinker lights respond). I'm lost at this point...

Can anybody offer any advice or a good starting point?

Thanks in advance!

Kevin Ostrowski

 

sounds like you might have a ground problem inside the light assembly, or you might be using the wrong bulb. if it used to work, I doubt the wiring has been reversed

 

I had a similar problem with my 82 E-250, turned out to be the light fixtures in the rear fenders were going bad. I got replacements at autozone and wired them in myself, wasn't hard. I am assuming that you haven't changed anything in the lighting circuit or parts since it was working.