What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

tail lights all died

cwalton

cwalton

1/2 ton status
Joined
Mar 7, 2012
Posts
176
Reaction score
0
Location
Andover, NH
Hey everyone, got pulled over this morning on my way to work cause my tail lights and rear side lights are all out; so im suspecting a wiring issue. Im hoping after work to fix it before i leave, but i dont know where the issue probably is and my wiring diagrams are at home. Can anyone give me a starting point or ideas?
 
If it's all that stuff then I'd suspect the harness that runs to the back of the truck. It's 4 wires molded together in a flat-ribbon type configuration. Going from memory, I think it's green/yellow/brown and black.

There is a harness connector near the fuel filler (round rubber plug) that might be corroded and preventing a good connection. I forget where the firewall side connector ends, but it might go into the bulkhead wiring near the fuseblock.

Simple test would be to disconnect that rear plug and test the wires for power with a DVM. If you're getting power down the harness then it's either a bad connection or lousy grounds in the taillight areas.

Good luck.

-G
 
Can't speak for the 69-72 K5s.

But on 73-87 pickup trucks, the stop/tail/turn harness connects to the 4-wire, molded harness (that Greg mentions) at the rear of the truck, inside the driver-side frame rail, behind the rear bumper. Its a round connector with about 5 pins (I think). I guess GM did that so you can remove the truck bed easier by just disconnecting the stop/tail/turn harness. So I don't know if that's how its set up on the Blazers or not.

Is there a fuse specifically for the stop/tail/turn lights? :dunno: I can't remember... Maybe start simple, and check for a burnt fuse, if you haven't already...

Also, when you use your turn signals, do the fronts still blink? On our trucks, when a bulb is out, the other light lights up solid, but doesn't blink. You can see this on the green-arrow indicators on the dash too. They'll just light up solid, and don't blink. Again, I'm referring to the 73-87s.

Just throwing other ideas out there.

:popcorn:
 
Thanks for the replies. I looked at the fuse panel/block and didn't see any burnt up bulbs. I didn't see a label for the rear lights either though. Haven't had much time to really get into it though, been too busy. Wiggled around the plug by the gas tank with no results, gotta check the firewall connection area when I get time. At least it gave me an excuse to pull my Camaro out early, as I've been itching to do.:rolleyes:
 
you will have a fuse labeled taillights.. every vehicle has one...
 
I had a similar thing happen a few months ago. Turns out that on my K5 there was a plug connector almost centered between the frame between the tank and bumper that had come apart. I plugged it back in and the lights worked again. I don't know if the wiring is standard. I've been finding a lot of things that have been "customized" lol.
Good luck!
 
ryoken said:
you will have a fuse labeled taillights.. every vehicle has one...
Click to expand...

I know i have a fuse... i was suggesting the 40 year old label has worn off so i couldnt spot which one it was. But like I said, none of the fuses were burnt up.
 
Last edited:
Still baffled. I pulled the plug out by the fuel tank and tested each of the 4 leads and all of them were hot when i had the light switch pulled out, and @ 0V when off. I then suspected a grounding issue (from what I gather all the lights ground essentially through the side panel running light?), cleaned up the grounding lead and still nothing. I'm not sure if something is getting lost in transition in the rear harness? I am frustrated and perplexed and have given up for the day. I also can't find my manual with the wiring diagrams which doesn't help me. Any ideas anyone?
 
move further down the system.. pull the bulbs one at a time and check for power at the contact in the socket...
 
ryoken said:
move further down the system.. pull the bulbs one at a time and check for power at the contact in the socket...
Click to expand...

Unfortunately I did that, I took off the bulb and tested for continuity from the socket to the ground and from the male connection to the socket. Also the lights work as blinkers or when the hazards are on..... I would have looked higher up stream if it weren't for the fact that all the leads were hot at the connection.
 
ok, I thought you said earlier you had no lights.. but it's just stop and park lights that don't work?
 
ryoken said:
ok, I thought you said earlier you had no lights.. but it's just stop and park lights that don't work?
Click to expand...

Thanks for taking the time to give me your feedback and thoughts by the way man. But yeah, initially I just assumed it was everything I guess, but today I noticed that the blinker action worked, they just aren't lighting up when the light switch is pulled out for night driving or whatever.
 
if the contact inside the socket has power with a test light with the headlight switch on, than you have an issue on the grd side...
 
Replaced the switch for the brake lights and that took care of that problem. Guess it was junk. Still working on diagnosing the running lights though.
 
You must log in or register to reply here.

Latest Posts

Top Bottom