Archived Battery discharge

[GMills]

Had a 4 hour trip yesterday and the batteries drained. Luckily I had a spare to put in to get home. If the alt goes, should I not get a code. The only evidence of any prob was the 'check guages' light when the volts dropped. Is taking the alt out and getting it bench tested the thing to do?

 

[crabman]

GMills,

1. Pull out both batteries and have them load checked.

2. Clean ALL connections to batteries, including engine grounds.

3. Check 120 amp. fuse in PDC box located in engine comp.

4. Bench check Alt.

5. Check for codes.

I did all this and mine still showed no charge. Decided to take it to a shop and have codes read with DRB. Started engine and it was showing charge! Did I "fix" it? Who knows! All I know is that if you do not have a DRB you can not track down certain electrical problems or do 98% of the checks in the Powertrain Diangostic Procedures book that I have.

I am now looking at buying a DRB.

crabman

PS If you do find your problem for sure, please post the fix!

 

[GMills]

It was the rectifier. All 4 diodes were gone. Any idea what would cause this? Shop says maybe a bad battery, any other ideas?

 

[crabman]

GM,

Did you load check the batteries? Clean all connections at batteries & grounds (on engine)? Do this before you install a new/remaned alt.

crabman

 

[John - K5AWO]

Ditto that warning!!!



never, but never, install a "new" alternator into a vehicle without testing for system status.





The diode stack blowing means that something shorted big time. Maybe one of the cells in the batteries. It might have blown the short away, but it will return.



Check for chaffed wiring on all of the heavy battery leads. Follow the steps previously mentioned.



Now, you can install the new alternator... .