I've been chasing a battery drain on my iroc all night. I finally got the test light to go out by unplugging the small multi-wire connector on the alternator. After a few searches, here and elsewhere, it seems this is caused by a failed diode inside the alternator. Some sights for other cars claim these diodes are readily available and can be replaced as apposed to replacing the entire alternator.

Is this possible on our cars? Would I need any special tools to do it?? Anyone have a quick rundown on where the diode is, how to get to it, and where to source a new one???

I'm a little hesitant to replace the alternator entirely because it's pretty new and only has a couple thousand miles on it.

Thanks for any help...

 

Most alternators come with a limited lifetime warranty. Even without receipt, most places will swap (they generally have your warranty ifo in their computer - advance, autozone, oreilly's do this). Check on a warranty replacement where you bought it at - I just replaced mine yesterday under warranty, and it's 10 months old - free replacement from advance!

 

... The stores will only replace the alt if you have your receipt OR it's less than a year old. No receipt and over a year old, forget it. They don't have the record of purchase in their computers anymore. And what makes things worse is that the receipts tend to only last about a year before they fade to useless (makes it difficult to replace a MAF or the like when it craps out a year and a half after purchase).

Which is why I rebuilt my 3 year old Lifetime alternator I bought from Advance back a couple months ago when the rectifier bridge crapped out. For $35 (kit from eBay) as opposed to $80 for a new alternator.

:edit: However, this all depends on the year of the car as well. Pre-87 cars have the SI alternator, and the diode can be replaced in ten minutes for about $5. 87 and newer cars have the CS, with which the whole alternator has to be taken apart to get the rectifier and regulator out.

 

Sucks that your Advance doesn't keep good records - both my local Advance and Autozone have warranty records on ALL my purchaces back to 2003!

 

Go to autozone. They still have the lifetime brake pads for my dads car that we sold 8 years ago...

 

Thanks for the help with this. The warranty idea was a good one. I couldn't remember where I bought it (let alone find the receipt) so I called around to see if anyone could find the purchase in their computer. No luck.

While calling around I found one store clerk that was privy to this diode replacement deal. The diode for my car was $56, the complete alternator was $86. Needless to say I just swapped in a new alt and the car is holding a charge fine now.

 

Autozone is even worse. Seems like every time I go in there they never have what I'm looking for (transmission oil, anyone?). I was even told that they couldn't test my ECM a couple of times, and I know full well they had the equipment and the manual to do so (Seen it myself a couple weeks prior when they had to hunt for the harness to test my ignition module). Only reason I went there for brake shoes back in 04 was because I had no other choice and NEEDED brake shoes. The ONLY thing I go to AZ for is batteries... Their DuraLast Gold battery is just short of the Optima in performance (75-DLG).

Besides, I'd rather rebuild my alternator with known good parts as opposed to having to run back and forth to the parts store half a dozen times before I get a decent alternator. Played that game, too.

 

I just rebuilt my alternator. Cost me $10 for a new rectifier and took about 30 minutes. New alternator was $100 + core. Many alternators can be repaired at a fraction of the replacement cost. It's not that tough.