hey all. ive got this problem with my 85 gl wagon.last month i replaced the heater core so i undid the dash,pulled it as far forward toward the steering wheel as i could undid all wiring harnesses and proceeded with the core exchange. all went well i put everything back as it was.now,when i drive it there are electrical problems.first the volt guage reads around 16-17 volts on initial startup with choke idle. when idle drops voltage drops to around 13.5-14 the normal range.while driving up around 3000-3500 rpm it picks back up to the high voltage. the only way i can control the voltage is to have as many accessories running as possible.the blower motor on high, radio on,lights so forth.now when ihave the blower past 2 my tach jumps around.when i have the blower on 4 and accelerate to the floor the car cuts out.i can turn the control from 4 to 3 under same acceleration and feel the cutting out dissapear.soooo.. italked to a alternator shop and they told me it could be an internal regulator in the alt.not sure if there could be a short to ground causing this sort of problem or what?by me taking the dash out could have something to do with it but i am pretty sure i put all back together right. maybe, maybe not?any suggestions?thanks

Retrace your steps. Just about all my wireing problems have been a simple problem in a hard spot. Follow the wires and make sure that they all go to what they belong to. When you break it down what goes where one at a time its not such a mess in your head.

Scooter, were there any short cuts to getting the heater out, I have a minor leak that I need to fix , looks like a lot of work for a small job, according to the manual.. Lang

Your symtoms sound like an alternator on its last legs (well the voltage regulator)

 

However....was this problem AT ALL apparent before you pulled the dash? That might clue you in.

Scooter, were there any short cuts to getting the heater out, I have a minor leak that I need to fix , looks like a lot of work for a small job, according to the manual.. Lang

Lang i dont think there is any easy way to remove the heater core.you have to pull the dash as far forward as possible which is up against the steering wheel in order for you to be able to remove the housing which holds the core.along with this you must remove the ac coil,glove box the center console and some of the plastic under the dash.the hardest part about the whole deal was getting the heatercore housing detached from theduct work that goes under the carpeting to the back seats.i ended up cutting the two spots where the duct meets the housing on the lower and when i reinstalled put foil tape back around the connection.be cautious about repairing the old core if you plan to do it yourself.that is what i did the first time i took the core out.i thaught i repaired the only visible cracks and pressure tested it with a gardenhose and it looked finebut a week later it started to leak again.so if you can find a new one that would be your best bet.good luck

Your symtoms sound like an alternator on its last legs (well the voltage regulator)

 

However....was this problem AT ALL apparent before you pulled the dash? That might clue you in.

its hard to remember if the problem was there before.i dont think so but still unsure.it seems like once i fix a problem with this car another follows close behind so it hard to tell.but that is next on my to-do list [retrace my electrical steps that is] then the water pump ,or maybe the other way around.thanks for the input.

Thanks Scooter, as I thought, bugger of a job. Have made a puller for the steering wheel so may use it for more room and also ditch the air con unit as its not working and dont need it, thanks again. lang

I had the same thing happen to me while I was driving down a mountain - a bad alternator is the ONLY thing that can cause you voltmeter to read that high unless the meter itself is defective. Disconnect the alternator, start the car, and see what volts you read. If it look at or below 12, you have a bad alternator. Replace it before you start to fry stuff (like a computer).