My 1995 Sunfire will not charge the battery... I took the alternater off and had it tested and it failed.. they told me at the parts place that my stereo probably fried the alternater but when I replaced it with one that was working in another car, my battery light was still on... I tried leaving the positive wire hooked up and putting a test light between the ground and the battery ground to see if I had a short and the light did not come on.. and if the car is running and I pull a battery cable off, the car dies. I tried the same test on another sunfire and the car stayed running.... Please, someone help! I have checked everything I could think of and at $150 an altenater, this is really starting to suck!
Wait, what did you replace? I'm hoping you mean to say that you replaced the stereo. Cause 2 fried alternators on one stereo would be mega bad juju.
Couple questions here to help clarify so maybe someone can help you:
Did you disconnect the offending stereo equipment? Did you do it BEFORE you put the new alternator in?
Have you had the second alternator checked yet? If so, what were the results?
Third- have you checked for any shorts in your wiring setup? PITA, I know, but it could be what's burning up your alternators has more to do with the installation of said stereo equipment than with the equipment itself.
Me no expert at electrical stuff..as a matter of fact I know about zilch, but these questions might give someone else somewhere to start when answering your questions.
I may not be the sharpest crayon in the box, but at least I'm a pretty color
Yes i did disconnect the stereo and the other alternator was out a car that was running fine.. i did not have it tested at the parts store but when the other car was running if i pulled a batter cable off the car would remain running so i guessed it was working... and i was told if i had a short and i unhooked my negative cable and put a test light between the negative cable and the negative side of my battery the light would light up but when i did that i got no light so i guessed there was no shorts in the system
Hi Andrew
NEVER disconnect the alternator with the engine running.
It is the fastest way to destroy the diodes- you MAY get away with it once but I doubt it will not harm something.
It used to be possible on much older systems, before solid state, but even then was not the best way to fault find.
The cheapest, simplest way to test an alternator is with a voltmeter, either a digital/analogue hand held type or the ones designed to fit in your car.
With a voltmeter fitted in the car you will always have an instant check that the system is working correctly, I even have one on my old tractor, which has an alternator conversion.
a. With the engine running you should have 14/14.5 volts across the battery terminals.
b. If not, try from the BATT terminal (the main output terminal on the alternator) to Earth/Ground where you should see 14/14.5 volts.
If you have the correct voltage at b. but not at a. then either the wiring is faulty between the alternator and battery or the fusible link has blown and needs to be replaced. If the link has blown and is replaced you should have the correct voltage at the battery and the charging system will be working correctly.
You might like to read this article which has some interesting info on alternators.
http://members.bellatlantic.net/res00d4r/alt_theory_rev/Alternator_Theory.html
Good Luck
Alont
how new is the bad alternator?
and how "powerful" is your stereo?
<img src="http://img.villagephotos.com/p/2003-11/504808/z28.jpg" width=317 height=59>
Hi Andrew
I think, after reading your post again that you "fried " the replacement alternator in your disconnection test on the other car.
Alont
i talked to to some guys at an auto electrical shop and what they had to say was the one i had tried replacing it was out my firebird and even know the housing and the hook ups where the same that the insides components are different so the computer will not see the alternator, he say ed to only replace it with one outa a 95 sunfire so im going to try that this weekend.. and ShefZ28 im running 3 Alpine V12 amps 2 are pulling 25 amps and one pulls 20 amps so thats an 75 amp draw, thats what PC auto figures blow my alternator to start with so i ordered an isolator and an extra battery and i gotta go pick up a capacitor , i was just afraid it was something eles and going on Thursday to get a new alternator and Putin it in and smoking it like right a way... i had a 1983 ford ranger that did that, we put like 5 of them in the dame thing, every time we figured we fixed it something eles would go wrong
Hi Andrew
this is a paragraph from the link I sent you
"L-Terminal: This is the lamp terminal and operates in the same manner as the CS-130 lamp circuit above. It is of interest to note that some applications use the ECM to send the L-Terminal a signal, and the F-Terminal responds with a signal sent to the ECM, in this application the ECM and the Regulator form a “closed loop” to control engine loading and alternator output."
This seems to be what the Auto electrical shop is saying, you need the correct alternator to complete the "Closed loop" circuit.
Alont
