Electrical issue: 1995 k1500

[Shitboxobs]

So I haven’t really dug into this too much yet but just looking for a place to start from someone that may have had similar problems.

I’ll start by saying I bought this truck a few years ago and shortly after I had an issue where all the brake lights would come on and stay on except for the cab light. Then when I hit the brakes the cab would come on and all others would go off. Also the truck would idle like **** when this happened. At the same time my wipers would go out along with my blower motor and parking selector.

I changed tail light circuit board, brake pedal switch, blower motor, checked fuses and still nothing. While checking wires under the hood I noticed a wire hanging from the hood light (that doesn’t work and bracket rusted off and is just sitting there) I picked it up and touched the spare wire to the cab and boom everything started working like normal. So I ground a spot of paint off, self taped it and everything was golden.

Fast forward about a year and I start having the same issue. I noticed the wires going to my wiper motor looking rough and one was actually broke. When I pulled on them the lights and all would go in and out. Sometimes fixing the problem for a few weeks at a time. I ended up cutting all the wires before the plug and butt connecting them but it changed nothing.

So at this point I’m sure I have a ground issue somewhere. Have also bought a wiper motor from my local salvage yard but haven’t installed it yet. Just wondering if anyone has had an issue similar to this and have any advise on something stupid to check. Attached is a bad pic of the hood light ground and my messed up wiper motor.

Thanks in advance

 

[LA2SD]

It sounds like you're on the right track. These old wire harnesses don't seem to hold up all that great. Poor grounds and exposed wires, where the housing has cracked or broken off, will cause issues. I'm chasing some electrical gremlins myself right now too.

 

[thinger2]

Start with the grounds. It is almost always the grounds.
Start at the battery and chase each wire and fix them all the way through.
You cant diagnose a tbi if it has bad grounds.
You cant tune a tbi if it has bad grounds.
Fix all of the crusty **** and then you can start to diagnose it.
Fix all of the bad grounds, find the shorts and repair them.
And then you can reset the system and make it run.
It kinda works like this, **** grounds, bad or no data.
Bad or no data or input out of range
Whatever?
On OBD2, you get much more feedback.
Obd 1 tells you something is wrong in that system.
Fix all of the grounds on the truck before you try to chase an electrical or performance problem.
And, once you do that, set base timing and learn all of the reset/ relearn procedures.
Its not complicated, its dumb.
The TBI is just a carb controlled by engine sensors.
It does all the things that we used to do with a screwdriver.
You just need to make sure that it has all of the inputs working correctly.
Fix all of the crusty **** grounds, all of them stem to stern.
Fix the vacuum leaks and vacuum hoses.
Rebuild the throttle body with the correct base gasket (there are two, only one is right)
Replace the fuel filter.
Set it at tdc and drive it for the next 15 years.
Done.

 

[Erin]

So I haven’t really dug into this too much yet but just looking for a place to start from someone that may have had similar problems.

I’ll start by saying I bought this truck a few years ago and shortly after I had an issue where all the brake lights would come on and stay on except for the cab light. Then when I hit the brakes the cab would come on and all others would go off. Also the truck would idle like **** when this happened. At the same time my wipers would go out along with my blower motor and parking selector.

I changed tail light circuit board, brake pedal switch, blower motor, checked fuses and still nothing. While checking wires under the hood I noticed a wire hanging from the hood light (that doesn’t work and bracket rusted off and is just sitting there) I picked it up and touched the spare wire to the cab and boom everything started working like normal. So I ground a spot of paint off, self taped it and everything was golden.

Fast forward about a year and I start having the same issue. I noticed the wires going to my wiper motor looking rough and one was actually broke. When I pulled on them the lights and all would go in and out. Sometimes fixing the problem for a few weeks at a time. I ended up cutting all the wires before the plug and butt connecting them but it changed nothing.

So at this point I’m sure I have a ground issue somewhere. Have also bought a wiper motor from my local salvage yard but haven’t installed it yet. Just wondering if anyone has had an issue similar to this and have any advise on something stupid to check. Attached is a bad pic of the hood light ground and my messed up wiper motor.

Thanks in advance

My hood light has been hanging for years with no issues.