Electrical Problems

[Gunnar Mason]

I once heard David Freiburger day that usually when an OBS Chevy hits around 200,000 miles, they start to have electrical problems. I’m starting to understand what he was getting at.
So far I have:
•A twitching fuel gauge
•A bad oil pressure gauge (sits at 20 psi at idle, jumps to 40 psi when I give it gas)
•A bad O2 sensor
•A bad wheel speed sensor
•Weak sound from back speakers
•A brake light issue

The brake light issue is the only one I haven’t figured out. When I barely touch the brake pedal, the brake lights come on. If I go any further than that, they shut off. The turn signals, hazards, reverse lights, and tail lights work, it’s just the brake lights that are the issue. Does anyone know what the problem is?

 

[454cid]

•A bad oil pressure gauge (sits at 20 psi at idle, jumps to 40 psi when I give it gas)

Is this a hot engine? What are you expecting it to do? This sounds completely normal to me.

 

[Eveready]

Most OBS electrical issues end up at a bad ground. Start by cleaning up all the ground connections and see how many issues remain. After that, some wires break internally and a specific item that isn't a ground might have a broken wire inside the insulation. A good test for that is to run a jumper in parallel to the wire that you suspect is bad. If the problem clears with the jumper you have found the problem.

 

[Gunnar Mason]

Is this a hot engine? What are you expecting it to do? This sounds completely normal to me.

Every other oil pressure gauge I’ve seen has always stayed in one spot, not moving around like this one does. I’m new to these trucks, so it could be normal I guess

 

[Gunnar Mason]

I talked to the owner of my local junkyard, and he said it sounds like a brake light switch, and he says it’s hooked up to the brake pedal. Could this be the problem?

 

[Eveready]

I talked to the owner of my local junkyard, and he said it sounds like a brake light switch, and he says it’s hooked up to the brake pedal. Could this be the problem?

Could be. Be sure and take before pictures so you can get the new switch installed correctly. Otherwise problems can appear. It at least would be a fairly cheap test.

 

[454cid]

Every other oil pressure gauge I’ve seen has always stayed in one spot, not moving around like this one does. I’m new to these trucks, so it could be normal I guess

Oil pressure changes with RPM, that's pretty standard for an engine. I will admit, when I've driven LS engine powered trucks the pressure gauge doesn't move much, which I thought was weird.

 

[PlayingWithTBI]

Most OBS electrical issues end up at a bad ground. Start by cleaning up all the ground connections and see how many issues remain. After that, some wires break internally and a specific item that isn't a ground might have a broken wire inside the insulation. A good test for that is to run a jumper in parallel to the wire that you suspect is bad. If the problem clears with the jumper you have found the problem.

I agree with Eveready on the ground wires inside the cab and under the hood. On the brake lights problem check the switch on the swing pedal assembly with a volt meter.

 

[Gunnar Mason]

Thanks for all the advice guys. Haven’t gotten around to trying anything, been swamped with work and school. It’s comforting to hear that most OBS electrical issues are just bad grounds. Also, I noticed the other night that the brake lights do come on again after they shut off. As I said before, if I tap it, the lights come on. If I go a little more, they shut off again. What I didn’t notice is that if my foot goes another 3 inches or so, the lights come back on. As long as it’s doing that, it’ll be less of a priority

 

[Crookedaxle]

I once heard David Freiburger day that usually when an OBS Chevy hits around 200,000 miles, they start to have electrical problems. I’m starting to understand what he was getting at.
So far I have:
•A twitching fuel gauge
•A bad oil pressure gauge (sits at 20 psi at idle, jumps to 40 psi when I give it gas)
•A bad O2 sensor
•A bad wheel speed sensor
•Weak sound from back speakers
•A brake light issue

The brake light issue is the only one I haven’t figured out. When I barely touch the brake pedal, the brake lights come on. If I go any further than that, they shut off. The turn signals, hazards, reverse lights, and tail lights work, it’s just the brake lights that are the issue. Does anyone know what the problem is?

I didn't know they had electricity in International Falls?