Ok here's the short story, I was heading home from work and 2 mins from my stop at a friends house the alternator belt squeal/slip thing starts going on and the volts on the guage jump to 18V I pull in and and leave it off for a couple hours, start it up and everything is ok so I head home(20min drive) no problem until 5mins from home then same thing happens squeal and 18V. I park it at home and pull the alternator belt and the alt pulley has moderate spin resistance but still turns, water pump spins just fine so I put the belt back on and fire it up but no start now. I have lights and hear relays and power windows but all are weak so I think the 3 yr old battery is finally toast. I'm thinking this weekend I'll be doing a battery/alternator/belt change so my what else could 18V wreck? 88 formula
Dash gage reads 18+ but could be higher. Runaway alt can wreck almost anything electronic... radio, ECM, etc... Motors likely won't care.
Carefully Check alt wiring harness section. If alt sees iffy wiring then new alt can have same problem. Check side plug and S501 is good. (service manual http://www.fieronews.net/fusion/downloads.php page 8a-30-0)
See my cave. alt sense in charge & start section. wire reading & wire service in general electrical section
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
It can blow bulbs, fry any/all electronics, force more current into motors than they can handle - same goes for wiring, but wires will be the last thing to go cuz fuses will pop first. Basically everything electric can overload from it in the long run. You'll find out when you have a properly working altenator/voltage regulator if anything else popped.
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10:11 AM
Marvin McInnis Member
Posts: 11599 From: ~ Kansas City, USA Registered: Apr 2002
I had that (overvoltage failure) happen in my Formula, too. It's probably the regulator in the alternator that has failed, or a broken wire or connection inside the alternator. I'd replace both the alternator and the battery. A failed alternator, especially an overvoltage failure, can quickly kill the battery, and a bad battery can lead to failure in an otherwise-good alternator.
As others have already said, overvoltage can kill anything electronic and dramatically shorten the life of light bulbs. Most motors will be OK, but too much voltage can sometimes cause DC motors to overspeed to the point that they self-destruct due to centrifugal force.
[This message has been edited by Marvin McInnis (edited 09-08-2011).]
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11:17 AM
ltlfrari Member
Posts: 5356 From: Wake Forest,NC,USA Registered: Jan 2002
I think the main issue is that it boils your battery, the acid leaks and then you've got white dust corrosion problems from now to eternity. When that happened to me I made a thick past of baking soda and water and slapped it one everywhere the acid had gotten, let it soak for a while then washed it off and repeated a few times. Not had any corrosion issues since.
If it still runs fine then it's not affected the ecm and that's probably the most delicate component on the car followed by the radio, so pretty much everything else 'should' be ok, although bulbs close to the end of their life might just get pushed over the edge.
Most times over voltage is caused by poor contact of the small connector on the alternator. Unplug it and clean the contacts on it and those in the alternator. Simply wrap some 200-600 paper around something long and thin enough to wipe the pins. That should fix it/
Ok I'm back, thanks for all the info. Had a long day making deliveries so nothing done except order the alternator, I will swap everything on Saturday since it will be below 100 for the first day since June lol, I will post a resolution if everything is ok Thanks
The '88s are different. The voltage sense connection to the regulator is internal to the alternator.
Source of info? CS130 still use an external sense wire. Wire doesn't do anything? Maybe some model uses a different regulator... Usually only a "one wire" alternator should be internal sense. (And only aftermarket uses one wire setup.)
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09:10 AM
Marvin McInnis Member
Posts: 11599 From: ~ Kansas City, USA Registered: Apr 2002
I was incorrect and have edited my previous post. From the '88 GM/Helm FSM:
The "sense" input to the regulator is indeed fed through the small, multi-pin connector at the alternator, via splice S501. The purpose of this may be to move the voltage sense measurement point closer to the battery. Verifying the location of S501 should confirm or refute this hypothesis. There is an internal +12v connection to the regulator shown in the GM schematic, but I don't know for sure what its function is.
My apologies to all for any inconvenience I may have caused.
[This message has been edited by Marvin McInnis (edited 09-10-2011).]
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06:15 PM
Sep 17th, 2011
kazew Member
Posts: 111 From: Oxford, MA / Phoenix, AZ Registered: Mar 2006
Problem resolved, I replaced the alternator and battery on Wednesday and all is fine. I basically wasted a week waiting for the alternator to come in at Autozone and a word of caution about ordering an alternator from them. I ordered the V6 alternator but what came in was the 4cyl alternator with the V6 part number on it, I reordered and they sent the same wrong part so try another parts store, thanks for all the replies.
Still see my cave. alt sense in charge & start section. wire reading & wire service in general electrical section
Some rewire should be done. At least rewire alt sense circuit to stop anymore damage risk to car if/when Fuse Link A goes bad.
Search fuse link or fusible link for rewire link A & B. Easier to move them now then on the road in dark...
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
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