I hate wiring issues

[87k5]

Hello to all CK5 members as I hope one of yall can help me. I have a 1989 GMC Sierra 2wd 350cid. My truck has 200,000 miles on it and I love it. Here is the problem. When I cut the headlights on the headlights come on but I have no tail lights and the instrument cluster does something wired, both blinker lights come on and stay on, high beam indicator comes on even though the high beams are not on, teperature/ volt meter drops to 0, and no backlighting. I have a feeling I am going to be told to check all of my grounds, if I am right can someone point me in the right direction as to what groud to check and where said ground can be found. I appreciate any help with this.

Thanks,
Charlie

 

[StevoandaRedK5]

I have a feeling I am going to be told to check all of my grounds, if I am right can someone point me in the right direction as to what groud to check and where said ground can be found.

With pretty much any electrical problem on these GM trucks, checking the grounds is usually the first place to start, especially with the symptoms you're describing. There are a few underneath the dash, but i don't know any specific places or for sure the exact number, so hopefully someone who knows the details will chime in.

 

[dhcomp]

Is it a 1/2 or 3/4 ton truck? I ask, because the 89 1/2 ton is an IFS truck, and completely different from the 3/4 and 1 ton 89's.

If its not a 1/2 ton, i say replace the headlight switch first. They are like $15, and well worth it, as all kinda of crazy **** happens when those go out. See if that fixes it.

 

[496truck]

If it IS a half ton, check the tail light socket assemblies. They were prone to rust and corrosion and would cause all kinds of electrical light issues. The socket assemblies were set up like a circuit board and the corrosion would build up and start connecting the different circuits together sending power back up the harness or eliminating grounds.

 

[87k5]

good help

Thanks for all of the replies, my truck is a 1/2 ton and it is 2wd I will look into the tail light assemblys and ensure all of the bulbs are not corroded. If I remember correctly one of the bulbs is really loose and works intermintly (sp) I think I am going to replace the bulb holder assembly and see if the problem goes away. Again thanks for the input.

 

[dhcomp]

Ok, i second checking the trailer wiring harness. If you have one, it often T's in between the left and right taillight harness right behind the hitch. THey often fill up with water and crap.