Hello Out there in Vetteland,
This is Marc again stationed in Germany where there are no US Auto Parts stores nearby...so here is the problem..
I posted awhile back that I took my 92 LT-1 out for a drive in the autobahn and noticed the headlights were dim and so were the instrument lights. then after awhile the digital readout began flashing on and off, and all the warning lights would flash like it was a game of keno or like a christmas tree. Then all interior lights went off, then the headlights...and minutes later, the car died. I towed it home and couldnt work on it as we were in training for a few weeks. Well I finally got around to her...bought a charger (she would no longer start after said incident) and charged the battery. Put it back in and she fired right up, no problem. Drove around and got these readings....
no load, 13.7 volts....headlights on, drops to 13.1 and digital dash gets slighter dim. start turning on accesories and she will go to the mid 12 range. Drive over time and operating voltage will go into the 12's, sometimes dipping to 11.9. I didnt want what happened to happen again so I took her to a german repair shop (Bosch) and they say couldnt find any charging problems, no battery problems, and no problems with the regulator. Are they mistaken or maybe just not familiar with my car?
after I went to pick it up I took it for a test drive and still the same voltages...and the funny thing, when I went in to pay the bill for them telling me there was no problem, I went back to drive her home and she wouldnt start. no clicking of the solenoid, so I am guessing its the start enable switch or vats. voltage at the attempted start was 13.4 according to the dash display. does ANYBODY have any idea whats going on here?
Thanks

Marc

 

The first time you got stuck, your alternator definetely was not charging the battery. The voltages are correct now except for when it falls below 12 volts with the engine running. I would check the battery voltage with a voltmeter and compare it with the dash voltmeter. The alternator is designed to operate at 14.3-14.7 volts and when it warms up it falls to 13.3 or so due to temperature . Your no crank could be due to dirty battery connections and I would remove and clean them and replace. VATS could also cause a no crank and an ohmeter connected to the wires from the ign sw (wires unplugged) with the key in place should read the same as the pellet. Try your spare ign key as its pellet is higher than your everyday key. At engine idle with heavy electrical load, the alternator cannot keep up, but when underway it should maintain higher than 13 volts. Defective rectifiers in the alternator could decrease its output and this can be seen on an oscilloscope and most modern ignition analyzers allow you to view the waveform across the battery.

 

I have a 87 that did the same thing. Took it to Auto-zone, the battery and alt. both checked out ok. They said it must be a loose wire somewhere. Well I cou;dn't find any problem with the wires so I took it to the dealer (still under warrenty) they replaced the battery (old one was 1yr.old) AND the alt. and now everything works GREAT. Their testing said both were bad, not charging enough and not holding a charge. I doubt they would of replace both if one was okay since they were paying for it. Hope this helps.

 

:cheers:

I believe you have an alternator problem

Turning things on really shouldn't effect the voltage

With these cars you can't run long under 13 volts

Start with simple stuff though first: clean battery terminals and alternator connections. Is the serpentine belt tensioner at it's worn out limit or is there still life in the belt?

See what happens, but your symptoms srtongly suggesr alternator. When it is cold it will be ok, as it warms up voltage will drop

:seeya

 

I also would vote the alternator is at fault. If a battery is not being replenished as you drive down the road, then turning on additional accessories will only drain it until the car stalls as you described. I would not suspect the cables since you were able to start it right up after recharging the battery. Good luck with your new alternator !
:chevy


[Modified by IndianaJef, 7:05 PM 11/15/2001]