Having a problem with my '88 4 Runner driver side brake light. When the headlights are off it works fine. When the headlights are on it doesn't work at all. When I first noticed the problem I removed the lens and replaced the bulb, it was burned inside the bulb glass was all grayish black. Replaced the bulb and everything worked fine for about a week. Then checked it again and it was burnt again same color on the bulb. Then I replaced the bulb with a long life bulb. It works with the lights off but not with them on, bulb not burnt this time. The wiring looks good but I'm not very good with electrical stuff. Also my license plate lights don't work, after replacing the bulbs that weren't burnt. The truck has a tow package on it but it doesn't look like factory wiring on the plug harness. I have no other issues with electrical problems on this truck. Just hoping someone could give me some advice.

 

Sounds like you got a short somewhere in the electrical wiring...I'd start with the tow package wiring for sure, especially if the end of the plug is left open; flopping around it could be shorting out on metal.

 

yeah I figured it was a short, but how do i find it ? Get one of those testers with the light that lets you know if you're getting curent thru the wire? Should I start at the bulb connection and work down or ?
Thanks

 

I'd try a visual inspection first for any damaged wiring as it only takes one little knick. I'd also cover up/cap off the metal prongs on the end of your towing package wiring (where it plugs into the trailer wiring) as I've seen them short out on the metal of the tow hitch etc. After a visual inspection and if you don't find anything, then it is time to find a friend who knows what they are doing w/ a multimeter to test your wiring.

You might try for some wiring testing tips.

Good luck.

 

Thanks waskillywabbit, just went out and inspected the wiring harness and it was wrapped around the hitch a few times and the wires seem pretty old and brittle. So I think I'll just go down and get a new 4 way harness or simply disconnect the old harness as it plugs in right underneath the driver side tail/brake light assembly.