gertie3993

iTrader: (2)

I was driving home the other day and my voltage gauge shot up to 16v. While idling it goes back down to 13, but goes back up as RPM increases. I had my charging system tested and I was told my alternator was bad. I replaced the alternator, and had it tested again. This time the battery was bad, so I replaced that to. The next day my alternator started shooting back up to 16v. I took it to be tested again and we found the load voltage to be normal, but no load was over 16v. I figured the voltage regulator was bad, so I got the alternator replaced. On the ride back from the auto parts store it started again. Does anyone have an idea what could be causing this?

Lurbie

iTrader: (3)

It's all to common to see a bad battery make a good alternator test bad (unless he tested it "out of car"). Since you've replaced both I'd suggest to start looking for a bad connection. If the generator senses a loss of voltage, it assumes a heavy load has been applied and increases its output to make up for it. Since no heavy load is really present, your voltage spikes up. Don't forget the connections at the starter and to make sure the ground to the alternator (engine block too) is good.

gertie3993

iTrader: (2)

Thanks, I have to buy a multimeter tomorrow and start looking into that. Now after I address any issues with the wiring, should the alternator still be good after spiking into the 16-18v range? Would the regulator have gone bad?

Lurbie

iTrader: (3)

It should still be fine, assuming the voltage increase is due to a low sense voltage.

gertie3993

iTrader: (2)

I was able to go through most of the wiring today. The only continuity problem I found was one of the fusable links. On the starter there are the three links, it looks like two merge to one connector, and one has its own separate connector. The single wire seemed to have a short. Do you happen to know what this wire is for? Also, would that possibly explain the problems I've been having?

Lurbie

iTrader: (3)

One of those definitely go to the generator, but looking at the 86 schematics I have, it's not real clear to me which one does, other than to say it is a red color (but depending on which engine the car originally had, all the others could be red too, or maybe red on some and rust color on others). If you can do a resistance/continuity test from the individual fusible links to the alternator, that would tell you which one goes where, but you have to disconnect them from each other for that test to work. Fusible links don't always "completely" blow like a fuse either, so test for high resistance. You can replace a fusible link, just be sure to get the same size and length of fusible link wire if you have to replace one.

gertie3993

iTrader: (2)

I found this schematic to be helpful. All the fusible link wires were red. I believe the two that merge are for the coil and distributor, which would mean the blown fuse likely goes to the alternator. Tomorrow I'll probably bypass the fuse and see if that fixes it. Then I'll have advance retest the charging system to make sure everything else is still good. Thanks for the help