Popping turn signal fuses 94 silverado

[Moparmat2000]

Hi everybody,

I have had this random problem with my 94 blowing turn signal fuses at random since this truck was about 5 years old. I bought the truck brand new. I would install a new 15A fuse, everything would be fine for a year or 2 then it would randomly blow again. Rinse, repeat. I could never find the problem. Once I'd put the new fuse in, everything would be working ok. Because of this, i could not ever duplicate to trouble shoot. Well now its finally permanently ground shorted I think. I get hazard lamps in the back, taillights, but no brakelights, no signal lights. My brakelight fuse is not blown. When I install a new signal light fuse, it pops right away as soon as I plug the fuse in. Anybody else run into this problem. I am thinking it's a ground short in the turn signal switch in the steering column that was intermittent, but now permanent. Anybody have any ideas on this? Or had the same problem.

Hazard lamps YES
Taillamps YES
Brake lamps NO
CHMSL NO
Turn signals NO

Brakelamp fuse GOOD
Turn Signal fuse BLOWS (right away)

 

[JWOK]

I think you are on the right track with the turn signal switch. The signal fuse blowing without activating the switch says you have a problem between the fuse panel and switch rather than after the switch. It still could be a wiring problem going through the column, but combined with your brake lights not working points toward the switch.

 

[JWOK]

Also be sure to check your flasher if you haven’t already.

 

[Nad_Yvalhosert]

So, 4-way flashers are good, parking lights are good. That eliminates a bad ground, probably eliminates a bad socket. It also means the wiring from cab to light lenses is good

Power flows from fuse, to brake switch, through multi function lever/turn signal, out to light sockets. You're probably on the right track. Get under the steering column, unplug the multifunction switch wiring and replace the blown fuse. Report back what happens.

 

[Moparmat2000]

I will unplug the column connector, and install a fuse to see if that isolates the issue. If it does then it's in the column, and it's time for a new turn signal switch. These arent too pricey, and not too terrible to change. I will check the flasher as well. I suppose theres 2 flashers. One for the signals, and one for the hazards. If it's the same part number, I may pull the hazards one, and swap it into the turn signals and try it. I have never seen a flasher become dead short like this though.

I will check my wiring schematics on the turn signal switch tomorrow to confirm that none of the wires in there is a ground wire, or if there is, which one it is. After I figure that out, i will unplug the turn signal switch at the column base and ohm it out. Should all read OL on the meter. If any of em is shorted to ground or shorted to one another when signal switch is off, that test will let me know.

Problem I ran into prior to this was I wouldent have signals or brake lights, I'd find a popped fuse. I'd replace it, and they worked fine. Could not duplicate, eventually thought it was my hoppy light mate trailer tow flat 4 way adaptor that was causing this issue, so I replaced it with a new one. Didnt have the problem for awhile. Just recently it's happened a lot, but when I'd replace the fuse problem went away. This last time, as soon as I would put the fuse in with key on, and signals shut off, I saw a visible flash as the fuse blew as I was installing it lol. So now maybe I can find this short that's been intermittent in my truck for oh about 22 years now, and i can fix it permanently.

 

[Moparmat2000]

Disconnected the column plug for the turn signals to try to isolate this. Still popping fuses. Anybody have any other ideas?

 

[Moparmat2000]

I get 12V across the contacts at the fuse, got a dead short somewhere between the fuse, and the column. The GM schematics are as clear as mud. Dont want to shotgun parts at it.

 

[Moparmat2000]

Thank God for the world wide web. On another GMT forum somebody had the same issue I do but with a 1994 K1500 5 speed. He stated that the turn signal fuse is wired with the reverse lights, and his reverse switch instead of failing open or closed, it failed as a ground short. Going to unplug the reverse light switch and see if I get signals and brake lights. Since this caused an intermittent issue over multiple years popping fuses randomly before failing for good.

I may not even bother to buy a new switch and hook it back up. I may run the wires for that back into the cab to a heavy duty toggle switch under the dash and turn them on only when I need them. The author of the article I found said he replaced the switch and all was well for awhile then the replacement shorted to ground in a short period of time. Not sure if they bought a cheapie replacement or a genuine GM part. That may be the reason I am thinking of just running a heavy duty toggle switch under the dash.

Now I gotta figure out where on the transmission the reverse switch is located. I pulled the trans once to fix a shot pilot bearing, only remember 1 plug on the side that's for the speedometer sensor.

 

[Moparmat2000]

Well I disconnected both plugs on the side of the transmission still popped fuses. I am out of 15A fuses so I am done with this for the day.

 

[JWOK]

I didn’t even think to mention the backup light circuit, sorry. My diagram shows one circuit leading to flasher and one circuit leading to backup light switch off that fuse. I do, however, have the Chilton manual which isn’t great. Did you try unplugging the turn signal flasher? If so, time to start tracing wiring to look for a short.