Just picked up my 4th van from same fleet. Reportedly this van eats batteries to a point where it can't be trusted on a daily basis. Supposedly GM could not decipher the problem. Runs great except the battery/volt light comes on, volt meter runs low, battery drains, vehicle dies. Sounds like a cut and dry bad voltage reg/altenator. Of course I will be checking that. I'd hate to think GM missed the boat on that! What else should I look for? Are there any known problem areas on these vans? Trying to meter out a volt drain on something with this much wiring would be task. But since I may need to, what sort of volt drain should it have parked and not running? Any thoughts/ideas appreciated!

p.s. Stewdogg, your info/help has been hugely appreciated!! If your ever in WI, I'd like to buy you a beer!!

 

I live in WI... Madison to be more specific.

What year is the van? I would think altenator first as well. How long does it take for a new battery to die?
Does it have a hood light? If so could the switch be bad and it's not turning off when the hood is closed(shot in the dark)?
Let me know how the generator tests.

 

Well since I live in Spring Green and work around Madison all the time, guess I owe you a beer eh? Anway, there is no hood light and so far no set time to battery drain. I put a meter in series with the negative battery terminal to monitor overall milliamp drain. Honestly, I couldn't get a reading that made sense (although it was higher than the same van parked next to it). Anyway, I think I am going to remove the Alt and get it tested then see what happens. Thanks again!

 

There is also a test proceedure if it isn't your alternator:

This is referred to as " parasitic drain " , all modern vehicles will normally have a small amount of parasitic drain for the various electronic control modules and constant memory for things like stereos, etc.

The test for this :

With a Multimeter set to DC amps , without the key in the ignition, doors closed and everything OFF

1 - disconnect the Negative battery cable
2 - attach one lead from the meter to this negative cable
3 - attach the other meter lead to the negative battery point

wait a few minutes for the reading to settle ( this is for everything to re-initialize ) and observe the reading, which should be somewhere in the ball park of .010 (milliamp) to .020 (milliamp). [ 1 amp = 1000 milliamp and 1/2 amp = .500 amp or 500 milliamp ]
This will depend on what accessories your vehicle has.

If you find a high reading , for example .500 amps ( 500 milliamp ), you can do one of two things to locate which circuit is responsible for the high draw.

#1

- leave everything connected as mentioned above
- remove one fuse at a time and see if the reading drops significantly

just remember to shut the door or disable the interior lights so they aren't on.

#2
- reconnect the battery cable
- pull one fuse at a time
- place one lead of the meter on one terminal of the fuse socket
- place the other lead of the meter to the other terminal of the fuse socket
- observe and record the reading

This will direct you to which circuit has a problem.

 

Had this problem and it drove me nuts!!!!! I found the dealer had incorrectly reinstalled the wire harness after replacement of the airconditioning compresser. There is a single black wire on the passengers side of the engine running from the alternator around the rear of the engine and what happened was the wire was shorting out to the exhause manifold intermittently and causing the battery to discharge. The wire basically tells the alternator when to charge the battery. Like I said it took me about three months to isolate the problem and yes I replaced the alternator and battery early in the process trying to resolve the problem.