84 has high voltage reading
Thread Starter
4th Gear
Joined: Aug 2005
Posts: 4
Likes: 0
From: Ypsilanti MI
84 has high voltage reading
A friend at work has an 84 vette.
while his wife was driving home it threw the belt. luckily it was about 1-1.5 miles from home. He went and got the car, and drove it home. After getting a new belt, he discovered that the Alt. had locked up and thats why the belt broke.
New alternator, new belt. Now when it was started with a fresh battery; the guage shows 17-18+ volts at idle. he immediately shut it down. After looking at the old alternator it was obvious that it had been going "full field" and burned up the bearings inside and locked up. It apears that the new one will do the same if the problem is not corrected.
The question is, what should the ohm reading on the exciter wire be? I believe he said that gm spec was 5-6ish, and its currently 1-2 or so. Also, where is the part of the system that he should be checking for a bad wire. IE, is the alt computer controlled? or is there a relay under the dash, or is it commanded by the elec dash? forgive me if some of the term are slightly off, I hope this is enough info for someone to give an idea of what to check next.
TIA for the help.
while his wife was driving home it threw the belt. luckily it was about 1-1.5 miles from home. He went and got the car, and drove it home. After getting a new belt, he discovered that the Alt. had locked up and thats why the belt broke.
New alternator, new belt. Now when it was started with a fresh battery; the guage shows 17-18+ volts at idle. he immediately shut it down. After looking at the old alternator it was obvious that it had been going "full field" and burned up the bearings inside and locked up. It apears that the new one will do the same if the problem is not corrected.
The question is, what should the ohm reading on the exciter wire be? I believe he said that gm spec was 5-6ish, and its currently 1-2 or so. Also, where is the part of the system that he should be checking for a bad wire. IE, is the alt computer controlled? or is there a relay under the dash, or is it commanded by the elec dash? forgive me if some of the term are slightly off, I hope this is enough info for someone to give an idea of what to check next.
TIA for the help.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Put a voltmeter on the battery terminals and start the engine, but shut it off if the voltage is really 17-18 volts because you can damage the cluster. The alternator's internal voltage regulator determines its output voltage and either the dash voltmeter is in serious error or the alternator needs to be returned.
Burning Brakes
Joined: Oct 2004
Posts: 838
Likes: 40
From: Long Island and Ocala Fl.
St. Jude Donor '09,'10,'11,'12,'13,'14-'15-'16-'17-'18-'19-'20-'21
A friend had a similar problem with his C3, it seemed to be an intermittant. He replaced 2 alternators before we discovered a bad connection in the main harness in the firewall connector. One of the pins had overheated causing a high resistance which in turn told the alternator to put out more voltage.
Thread Starter
4th Gear
Joined: Aug 2005
Posts: 4
Likes: 0
From: Ypsilanti MI
so far, I know that he has verified that the voltage reading is accurate compared to the dash guage.
Ill see him at work next wednesday, and point him to this forum; so he can respond better than going through someone.
Ill see him at work next wednesday, and point him to this forum; so he can respond better than going through someone.
