I have a 1986 S10 Blazer 4x4, 2.8L. The truck has some sort of short and I cannot seem to trace it. Especially when it is not shorting out so it shorts intermittently like every other day (wierd). When it does short or whatever it is doing ... when I turn my headlights on or parking lights the battery charging light will go down slowly to 9 volts. Also the turn signal lights on the dashboard will come on and stay on and the other guages like oil pressure and engine temperature will change. Also when my headlights are off, and I use the turn signal (either left or right) the battery guage will move down gradually to 9 volts as it flashes. And also again with lights off and I turn on the radio the battery voltage will drop. And if I use the cigarette lighter the voltage will dramatically below 9 volts. The battery will not drain when turning on the wipers or heater fan. I did pull the headlight switch since it was the easiest to get at, so that has been eliminated. Any ideas on how to find the culprit?

[IMG]local://upfiles/14203/041779F0FC384E778579EAC6642E5FD8.jpg[/IMG]

 

try checking ground wires under the dash below the steering wheel to the left. Had a similiar prob on an 88 i had, gauges would bounce all over the place. good luck.

 

http://econtent.autozone.com:24991/z...528003db86.gif

This may help

 

I think its fixed. I replace the instrument cluster dimmer switch and I guess I'll know for sure by tomorrow since the short only happens like every other time I start the truck. Thanks to rdhack from his posting on "Wierd instrument panel" am also going to check more wires under my steering wheel column to be sure and since its an old truck. THANKS MUCH GUYS!

 

I replaced that dimmer switch and it worked for awhile but now it's acting up again. While idling with parking lights on, turn the dimmer switch back and forth the battery guage goes down to about 10 volts and the other guages change or move about a 1/4". If I turn the dimmer switch to dome light the battery guage or charging goes back up to normal. With the dome light on and I open the door the battery guage goes down again.

Does anyone have any other theories for me?

 

i ended up having a similar problem. first i changed out the battery thinking that was it. then it ended up being the alternator. no clue why it decided to go out like that. just did. most probably the internal regulator going out.

 

Any progress on this problem? I'm having very similar issues with an 89 suburban. I turned on my headlights last night after work and the whole truck shut down. (engine stopped, lights went out, not even the CEL stayed on).

It was like I shorted out the entire car. After screwing around for an hour and repeating the problem, car seemed to fix itself and I was able to get home.

When I got home I couldn't re-create the problem by turning on the headlights, but if I turned the dimmer switch all the way to the dome light position the CEL would come on and the engine would start to stumble? If I quickly turned the dome light off, everything would return to normal. Really freaky.

Other weird things, coolant temp gauge swings wildly around to really high temps (even though it is 15 degrees outside). Also in the past few weeks notice Voltage gauge would sometimes just drop to 12 volts..and headlights would dim...then seem to just come back to 13 V eventually.

 

I was having the exact problem quik1964 had and sure enough, after digging out a huge mess of wires, I found a ground wire with a broken mounting ring on the end. After replacing that and remounting it all my bouncing guages and "draining battery" problems were eliminated. Glad I found this thread