Goathead666

I have an '88 4x4 pickup with the 3vze, recently had the running lights go out on me. The fuse keeps blowing and the bulbs look good, all four corners don't work but brakes, and turn signals are fine.

Wondering if anybody could point me to a wiring diagram or maybe a couple other things to check out, put a 20 amp fuse in just to check and that blew as well, seems like a pretty hard short.

thanks,

Rick

abecedarian

sorry for the file sizes:

http://abecedarian.toythieves.com/po...s_wiring_1.jpg

http://abecedarian.toythieves.com/po...s_wiring_2.jpg

Goathead666

Thank you, I'll see if i can't get this bastard working, not much fun driving with no tail-lights and tapping the brake to let people know you're there.

Goathead666

Looks like my problem may be that taillight relay, controls the front marker lights as well. Any chance you know where I can find that in my rig?

abecedarian

should be in the panel under the dash, to the front (closer to the firewall) from the turn signal flasher
have you tried pulling all the marker lamps to see that they're all installed properly?

Goathead666

They all worked about a month ago, just started frying fuses and can't figure out why, I'll recheck the bulbs again though, maybe I missed something, I'm guessing it has something to do with that relay in line there. What about the dimmer switch, the diagram shows that it's remotely connected to that as well?

abecedarian

by the diagrams, the tail light fuse protects only the marker / running lights.
I might be suspect that one of the rear brake lights may be causing the issue since they are dual filament bulbs.

Goathead666

Well the marker and running lights are the only ones that aren't working so I'm not sure if the brake light bulb would effect that fuse, hell I don't know.... I guess I could replace all four corner bulbs with brand new correct bulbs and go from there. The previous owner may have put the wrong bulbs in? I checked the relay here at work today and it seems to be working just fine, so the problem is elsewhere.

Anybody know the correct model # for the running light bulbs and the front marker bulbs? Just a shot in the dark.

Rick

abecedarian

Brake / rear running lights are 1157
front corner / marker lights are 194

One thing I used to do troubleshooting shorts was to use a self-resetting breaker with a couple of male and female blade connectors and pieces of wire spliced into like a pigtail that slipped in the fuse holder's terminals in place of the fuse that way I didn't blow fuses or wiring and I could walk around and look at the lights and see what was and wasn't working when the breaker would reset itself.
As for the rear lights, what I meant by them being a possible cause is since they are a combined bulb, if corrosion or something managed to short between the running light circuit and the brake light circuit, the extra draw of the brake lights could be enough to blow the fuse.
Do you have a trailer hitch / wiring adapter on the vehicle?

Goathead666

Yes there is a wiring adaptor for a trailer plug, didn't even think to look at that. Thank you for the part#, I'll pick up some on the way home. I like the idea of the self resetting breaker

abecedarian

I've had those adapters go out and cause fuses to blow so maybe disconnect that puppy first and see... maybe you'll save some money on bulbs.

Goathead666

Thanks dude, I'll give that a shot when i get home tonight.

desertcox05

i have found a short inside a bulb before. it wasn't tripping fuses but it was making dash lights do strange things