: 02 EXT - Battery Not Charging, Alternator OK, Wires OK, what next?

11-14-10, 12:13 PM
Volt Meter on Dash is reading about 12.
Sometimes jumps up to just over 14 (intermittently - but less and less frequently).
If I drive the car, the voltage gradually decreases until the car dies.
The moment I disconnect the battery, the car dies. (Been rechgarging with Battery Charger between)
I assumed it was the voltage regulator internally after doing much reading here.
I found the identical AC Delco Alternator (part#15750871) at a local salvage yard for only $30.
I picked that alternator up and immediately had it bench tested at Pep Boys...
That tested fine and I got a print out showing the results.
I made sure all connections were clean and installed the replacement.
To my dismay, the Volt Meter on the Dash is still only reading 12, and when I disconnect the battery the car dies.
I changed out the cable that goes from the alternator to the connection in the red plastic box, no change.
I found an old handheld digital Voltmeter I had and when running the vehicle and testing from the Alternator, it SEEMS to be putting out the right amount of voltage (ranges from 12-16 on this meter, but mostly is just over 14).

I have no idea what to check next.
I traced the other wire from that red plastic box over the top of the engine to a part which is shaped like a small black oil filter. There is another wire going from there to what I assume is the computer. All wires and connections seem fine. Please help - too broke for stealership visit. Thanx

MORE INFO? / BACKSTORY (only read if you need to)
My girlfriend has a 02 Escalade EXT. Recently her battery light came on and she (without telling me) took the car back to Sears and had the battery swapped as her DieHard had plenty of warranty left. Yet the battery light remained on after the swap. Apparently this was the case for a month or so. One day she calls me while driving and tells me she lost power to radio and other accessories and the Volt Meter on the dash is going down. You guessed it, 5 minutes later, another call and she was on the side of the road, the car just died as she was driving. I pulled the battery, brought it home & put it on charge over night. The next day, I put in the battery. At first, the Volt Meter was only hovering around 12. I drove the car for a little while and to my pleasant surprise, after about maybe 10 miles, the Volt Meter jumped back up to just above 14. Nevertheless, we went to Sears that night and they ran in-vehicle tests all of which passed... again, at this time, the Volt Meter on the Dash was showing just above 14. So I told her the vehicle seemed OK and to keep an eye on it and drive running accessories. The next day, The Volt Meter never went above 12 and after driving for a while, it started to dive again until the car died (just like before). I assumed it was the voltage regulator internally because of the intermittency.... so I did not bother bench testing the original because our own experience was that it would work fine, then not at all, back and forth. I assume that the month she had been driving the car with the battery light on, the charge would fall off, then kick back in... but I believe that the frequency of the charge falling off increased to the point where now we can't drive a single day without depleting a fully charged battery.

Sorry if that was longwinded.

11-14-10, 12:20 PM
One more note (may or may not be related, but is electrical)...
Her OBD / Cigarette Lighter fuse keeps blowing... I needed to access the OBD so I used a 20amp (don't recall, but is only supposed to be a 10 or 15)... Actually, when I looked, the previous size used was a 20. The 20amp fuse I used blew again after just a couple/few weeks. I did not even realize it until we were having these alternator problems and I went to access the OBD. I again put a 20amp fuse in... I doubt it's related, but you never know what strange things lurk beneath a hood :)

11-14-10, 09:53 PM
sounds like (if the battery and alternator are both good) that there is a short or slow drain somewhere in the electrical system. What sucks is that they're usually not very easy to find. If the battery is good, and the alternator is also, and it keeps dying, then SOMETHING has to be draining the battery. Sounds like a long slow painful process of isolating an electrical draw issue.

11-15-10, 02:41 PM
Thank you for taking the time to respond.

I feel so stupid... Found the problem... reinstallation of alternator was rushed and done in the dark... Looking at it today, I realized I failed to plug the connection in back on top. Everything is working fine now - LOL.

I wish I could just delete this entire post.

11-17-10, 02:55 PM
Well, since I can't delete it, I want to share a tip at least...
I wish I had taken pix along the way.

When I got the mounting bolts out of the Alternator, it did not just come right out.
There are Spacer/Sleeves that go between the bracket and the alternator on the pulley side.
Basically, as the bolt is screwed in, the head comes into contact with a Spacer/Sleeve and pushes that against the Alternator body to snug up the fit (bolt inside spacer/sleeve inside bracket mounting hole up against Alternator body).

Again, I wish I took pix. The car is not here now, but if I can get a pic of this spacer, I will post it.

Anyway, those of you who have already performed this task know what I am talking about.
Once the bolts were out, those sleeves were so snug against the alternator that I could jiggle it, but not get it out. I used a big long screw driver to gently pry the alternator up and out.

Here is the tip... Foreseeing the tight fit and probable forcing of the new unit in, and having had experience with similar situations on other vehicles, I used a very simple and quick solution. I simply took a socket that was larger than the spacer and held that over the spacer on the radiator side. I used a small c-clamp to force the spacer 'into' the socket... I only had to go a couple/few turns. I was only trying to create some clearance for reinstallation. The replacement alternator slipped right in and the bolts snugged the spacers right up to a perfect fit.

Again, I wish I had taken pix of the entire process. But I hope this tip helps someone avoid the hassle of trying to force and pound a replacement alternator in between those spacers, or from using a method which might damage those spacers.

Anyway, Cheers.

11-18-10, 11:28 AM
OK, here are the pics...
I've outlined the sleeve/spacer in the first pic (rusted).

In the second pic, I positioned the socket and c-clamp for reference...
With the bolt removed, the socket will snug up against the bracket (so that the recess of the socket will accept the sleeve/spacer when tightened) and the c-clamp head would go on the other end of the sleeve/spacer (with the alternator removed).