I've searched on here as much as possible and I haven't seen this problem on here. All of my lights work accept the dim lights and also the daytime running lights/automatic lights at night time. Every now and then they will work for a minute and then go back off. I've had two people check it and both say power is getting around like it should. I have ordered a headlamp switch and am picking it up after work. Also the windshield washer/spray pumps aren't working either. Could these be two separate problems or one? I've had some say it's the light switch. Also a few have said they believe the multi-function switch on the steering wheel is the problem. After studying this forum, I'm not sure it isn't the sensor on the passenger side dash covered by the speaker screen. I've pushed that a bunch and no luck. When I click the lights on bright they will work and the park and brake lights always work when I turn them on with the switch. Don't think they ever come on automatic. I just bought the blazer and it had that problem when I got it. The alternator went out a week ago and has been replaced. I hope the switch that I get today fixes the problem. I know it's not fair to expect a definite answer from anyone, but I would like to hear from someone who has a pretty confident answer based on the information I provided. We have checked all of the relays that we can find. There may be one more up under the dash that we haven't checked/found? Don't forget the windshield wiper pump don't work either and they are connected with fluid. Haven't checked for power on those yet because I just now saw they aren't working. Any help is appreciated and as always, be good to your fellow man.

 

2 door, 4 door, ZR2 or not? It all makes a difference with diagnostic procedures.


Headlamp circuits are quite complex on these vehicles because there are several things that control them: headlamp switch, autolamp system, flash to pass, hi/lo dimmer, daytime running lights, and the park brake mechanism in some cases. Some, but not all circuits go through the multifunction switch. They are mostly controlled by isolated grounds being switched through relays as necessary, not by switching battery voltage alone. Diagnosis will require a DVOM, a good working knowledge of DC circuitry, and lots of time & patience. We can supply the schematics and the guidance, but be prepared for some serious wire tracing, and a LOT of testing


Or you can try the "shotgun" approach of aimlessly replacing parts, which may or may not fix the problem. Depends how good of a guesser you are


02P23

 

4 door 4x4 not ZR2 4.3. I don't have a good working Knowledge of DC circuitry, but I have a good engineer that is doing this for me.

 

The light switch wasn't the problem. It's one of the wires in that group of wiring going from the steering wheel up under the dash. I don't know which one for sure yet. When I lift up on those wires, the lights will come on. When I let go and let them fall back into place, the lights will turn back on. Any idea on which specific wire it's going to be? I wasn't in my garage working with it the other night and it got dark. So I just put it back together and used my bright lights to get it home. I have some other problems that came yesterday on my way home from buying some interior trim at the wrecking yard. Will be posting that next. Thanks for the help.

 

There are several headlamp circuits in the column. In your case, you have narrowed the problem area down, so it will be easier to locate the poor connection, than it would be to trace each wire individually using an DVOM.