I am having issues with my charging system. I have a 1984 pickup, I have replaced both the alternator and the Voltage regulator. Still was not charging I again removed the alternator and had it tested, was working fine, reinstalled it and installed another new voltage regulator. Large problem now charging nearly 50 volts. YES I know that is impossible, but believe me I know how to run a voltmeter and yes that is what it said. I then purchased yet another regulator and checked the output voltage of the alternator it is about .5+- volts. I have checked all the fuses and even tried looking over the wiring harness for any problems, fuses are all good and I couldn't see any problems with the wiring. I don't know where to go from here any ideas! I feel like I have hit a dead end.

 

Are there any fusible links? Try using an ohmeter to make sure no wires are broken.

 

Yeh ran checks on all wires everything seems to check out. All fuses are good, pulled and check visually and with guage.

 

I am having the same problem with my 1984. I have tried the same things you have and nothing is working. HHEELLPP!!!!!!!

 

A friend of mine has an 85 Toyota pick-up...his charging system was also not working. It turned out that about 2 inches from where the harness plugged into the alternator that it had a broken wire inside the insulation(tiny 16 gauge wire). I think I used the ohm meter function to ohm it out with the plug dis-connected from the alt. Once I repaired the hidden open the charging worked great.....finding that open can seem intimidating to many but it's not that hard.

The alt harness has a couple wires going directly to the black regulator box mounted nearby on the fender panel I think.....so it's an easy thing to ohm it out. I'm probably remembering it wrong but a white with black tracer stripe wire comes to mind as the issue with my friend's 85.

 

I would look real close at your ground cables and battery terminals.

Also the wire coming off the alternator B terminal gets burnt and brittle with age.

Also look at the female side of the plug going into the alternator a little corrosion can cause a no charge issue as when you replaced the alternator and it worked but did not charge your battery.

Bad battery heat kills more batteries than cold

 

my alternator is brand new and tested on machine before bringing home and installing. external regulator brand new. Still not charging. Three wires going into the back of my alternator: red, white and yellow. The yellow wire has 4 volts and thats all the power going to my alt. HELP....

 

Might be time to find a mechanic.

:wabbit2:

 

That doesn't sound like a Toyota factory alt with only 3 wires of those colors....sounds Chevy.

 

The alt is for a toyota. Come from AutoZone. I talked to a mechanic over the phone yesterday and he said it sounds like something burnt out around the ignition.?????

 

Good News... Fixed my problem. The red wire coming from the back of the alternator is suppost to have 12 volts going to alt when key is turned on and mine didnt. Traced it down to the fuse panel on the inside and noticed the power source that was suppost to pwer it came undone.