Battery overcharging and checking Fusible Link (1 Viewer)

[jonah111]

I'm having a problem with the battery overcharging on my 2000 and I'd like to make sure that the issue isn't with the fusible link before I replace the alternator. Battery is at 12.1v with signs that is was leaking- moisture on battery and the surrounding area. Battery light is on at idle, but appears to be charging and reads 14v. When the idle is brought up to 1500 rpm, charging goes up to 16.8v. While my daughter was driving, she says the voltage gauge was pegged at 18 and there were multiple warning lights on the dash. If I hadn't done any work on it recently, I'd just change the alternator- it's at 250k and I'm pretty sure it's original. BUT- I just got done changing out the AC compressor two days ago and it seems like at bit of a coincidence that this failed. I've had my share of repairs that required a couple of attempts to get it right and I'm wondering if I damaged the fusible link wiring while manuvering the old compressor out through the top. I've checked the 7.5 amp fuse and cleaned the contacts with CRC electronics cleaner. Is there any way I can test the wiring connections to the fusible link? I tried checking continuity between the fuse contacts and there is none. Meter shows 11.8v at the fuse contacts with the ignition off.

The problem seems to have started gradually after about 50 miles of driving since the repair. Last night the battery light was fading on & off, today it came on and stayed on, along with the other dash lights.

Thanks for any input!

 

[jerryb]

nm

 

[KillerBox]

I had the same problem in my past. It ended up being the tiniest amount of corrosion on the Alt-S fuse. You could not even see the corrosion.

Steps I took to correct my over-voltage problem:

1.) Turn engine off
2.) Open up the little fuse holder on the positive batter post. Remove the Alt-S fuse (it pulls out easily).
3.) Spray some plastic safe electrical cleaner down in the fuse holder.
4.) Put a little dielectric grease in the fuse holder after the electrical cleaner dries for a few minutes.
5.) Reinstall the fuse and crank the engine and check the voltages.

 

[KillerBox]

After reading your post and you have already checked the Alt-S fuse, then my next step would be to see if the small wire connector for the sensing wires on alternator is fully connected.

 

[jonah111]

Thanks for the suggestions- I'll look over the alternator wiring tonight. I ordered a remanufactured Denso from Rock Auto in case I need to install this weekend.

 

[abuck99]

* ALT-S fuse on later model years is located inside the engine room fuse box just behind the battery.

 

[B4scott]

I had the same issue on my 2001.. The battery light would flicker, but the other lights would stay on until i restarted the car. Unfortunately, I had already replaced the alternator a few weeks ago before I read this.. Obviously the alternator didnt fix the issue. I just cleaned the ALT-S fuse and it all works fine now for at least the last 2 days... Oh well, at least I now have a new alternator that should be good for another 20 years..

 

[jonah111]

Just to follow up, my issue was resolved when I replaced the alternator. Thanks for all the input!