Apparently the alt on my 89 isn't working, as the battery has slowly died over three days. The alt is newer, I would say less than a year. Can I test this with a voltmeter? I did check the pole with the batt cable to it disconnected, and got .56 volts, but I'm not sure thats how to check it. It is getting 12v at one of the poles, I'm guessing thats the signal wire for it.

Any suggestions? The people at autozone by my house are useless and I would rather test it myself.

Jason

 

To start , use the same language that others use in the repair bis. then we do not have to guess what your talking about " pole " ? , the guess is battery connection , but which one ? positive or negative ?
The regulator is in the computer , and the computer grounds the connection to the battery if it sees a need for charging , with all other conditions met , like engine running , the computer needs a signal from the crank sensor [ this is just one more of the things that change from yr to yr .
There are 2 small wires on back of ALT. , find the one going to computer and disconnect , then with eng. running , use a jumper wire to ground the connector on back of the ALT. for only a few seconds [ this full fields the ALT. , which can over heat the ALT. ] , with a multimeter connected , you should see 14.5-16 volts , also if you had an amp meter there should be about 120 amps .
If not then the ALT. is bad , or you may not be testing correctly .
If it does then something else is wrong , like the crank sensor , all repairs/replacements , should be suggested by testing .
A yr. old ALT. can be bad , do not assume anything is good or bad with out testing .

 

Non IC's didn't have a computer. They have the old school voltage reg. Testing is similar. I think there is something in the sticky about it.

 

I looked in the sticky but didn't see anything on that, except to change later years to early style regulators.

The .56 volts I got was off the fat cable that goes to the battery. One of the smaller poles has 12v with ignition on, the other one didn't show any voltage. I'm confused here, I thought it was internally regulated.

Jason

 

Ok I have figured out it is externally regulated, and going by the wire diagram I came across, it must be getting power as I have power at the alt at one of the small wires. Should I test the alt like John said above, and if it tests ok assume the regulator is bad?

Jason

 

.56 volts from the cable to ground? Coming from the alt end or harness end? That is supposed to be the charging wire. Should be a clean and very good connection to the battery.

 

Coming directly from the charge pole on the alt. I checked all connections at the batt and the connectors that are inline on the charge wire from the alt to the batt.

Jason

 

Mine 91 is charging a little on the high side. 15.1volts and 14.9v with the headlights on. It has a new battery too.