I have a 1995 S10 Blazer 4x4 4 door with 125,000 on the 4.3L. Just purchased it and have worked through a number of problems which I can thank this forum for. One of my last issues is the alternator output. I replaced what I thought was a bad alternator which was reading mid 11s on the voltmeter at the alternator. The new alternator put out 14.2ish for a very short time and then dropped to 11.4 consistently. I replaced the new alternator which Autozone tested and said was fine but replaced anyway. The 2nd new alternator was putting out 11.4 but I've since replaced the battery and I'm now getting 12.18v. I have no aftermarket stereo or anything else. The engine runs fine right now and starts great, I have not driven it since replacing the alternator since its on jackstands. I put the blazer in drive and give it has and no change in output. I'm not a certified mechanic, but I have a pretty good understanding of things and do all my own work. Any help is appreciated.

 

Anybody?

 

This I do not know what the problem could be, but i'm sure someone does
but the forum rules state that you must wait 24 hours to bump a thread if you have not received a response

 

Still looking for some help, I've just replaced the belt which was a little stretched. I still have not corrected the issue. There should only be the one 1 "L" wire in the connector which has 12v roughly with the ignition on. There are two wires which run from the alternator post, 1 goes to the battery, the other intO the harness but I'm thinking toward the PCM. Good connections, I tried grounding the alternator case to a body bolt and the neg on battery with no change......anybody? The '97 has 3 wires off the post on the alternator, if you have a 95 can you check your alternaor and post a review?

 

Well, I checked the fusible links, 2 coming off the pos battery post and the one coming of the back of the alternator-all good. I ran a ground wire from the alternator case to the frame for testing purposes still no luck with this issue. Battery is reading 12.4 v and output on alternator is 11.98v.....this is driving me mad...I've held myself back a few times from throwing tools at this thing...any help would be appreciated, for my Blazers sake.

 

Maybe try changing the battery cables? Check, clean and tighten any grounds?

 

i had a similar issue. I do have a large stereo system but I also have a 1200 cca agm battery. My alternator stopped charging the system to the normal 14v. The next day I swapped to a new ad244. It popped up to the 14v range but dropped. i am now going through the wiring. I think the main power wire to the alt is bad. I plan to do a big 3 upgrade and rewire the whole system. With the new alt the only issue i can think of would be the alt is not the normal pcm activated one and it is causing the issue. we will see.

 

Well I about gave up and brought it to the mechanic. I decided to have the Autozone test the 2nd new alternator in a week, turns out it was bad. Replaced with new one and wouldn't you know, all is well. While I was at AZ they told me they don't recommend the Valuecraft line because they're remqnufactured poorly...a word to you all.

 

I do not get any parts from autozone, never had good luck with them.