Hi,

I was checking out my battery, since when I have left my GTA unused for a few weeks, the battery seemed weak.

Well, it has been sitting for 3 days now. The volts read 11 volts (approx) on my analog multimeter. And the guage in the car reads at 4 lines below 13, which I think means 11 volts too.

I put my multimeter on the "amps" setting, and tested the amps by hooking up the leads to the pos terminal of the batt and the to the pos cable (in series at the pos terminal). This is with the car off, of course. I pegged the amps reading to the right on every setting, and blew a fuse in the multimeter too.

I also hooked up a test light in series the same way, and the light came on fairly brightly, but not as brightly as it does when it is on the pos and neg of the battery.

I suppose this proves I have a parasitic drain on the battery. Could it be that the amount of "normal" drain would make the test light glow ?

Or do I really have a drain to find and fix ?

Also, on the multimeter, for amps, I have 3 settings : 0.5, 50, and 250. I am assuming that the safest setting to use is the highest, 250. Don't want to blow another fuse.

What is the most likely cause of a battery drain ? I was thinking the rear hatch, since someone I know had that problem.



Thanks,

GTA88

 

Typical mulitmeter fuses (like in a Simpson 260 or something) are 1 amp. These fuses are rated to blow within about a half hour at twice their rating, and within a second or so at 10 times their rating. So if you hooked it up and it blew it right away, you have a sizable drain, like probably 5 amps or more.

The only good way to find it is to first get an ammeter with a 10 amp range (your 260, with the leads plugged into the 2 10 amp sockets, would work fine) and start disconnecting stuff until you find what makes it go away. I'd suggest unhooking stereo equipment first; then the big red wire on the alternator; then the little terminal board on the driver's side kick panel above the hood release assembly, one wire at a time; then go through the fuse box one fuse at a time.

 

Update : I unhooked the battery wire at the alt, disconnected the 3-pin connector at the alt, removed each fuse one by one, replacing each one after testing. STILL getting the test light to light up every time !! Arggh......

 

So what about those other things? Did they make any difference?

 

So far I've only done the alternator wire from the battery and the 3-pin connector at the alt. "Big red wire" I guess is going to the 3-pin connector, which I have removed... Have not checked the terminal by the driver's feet, or disconnected the radio. Wouldn't pulling the fuse for the radio be good enough for the radio test ?

Same for the rear hatch. Wouldn't pulling the rear hatch fuse test the rear hatch for draw ?

 

Pulling the radio fuse would be OK, as long as there's no other amps or whatever in the car.

The terminal board above the hood release cable thing is where all of the car's optional power accesories get their power from. Power seats, hatch defogger, etc. etc. Each of those optional circuits has a power lead that plugs in there; either to ignition or to battery. If one of things is where your drain is, pulling fuses won't isolate it.

It's not impossible that one of your headlight motors is defective also; you might want to disconnect each of those while watching your ammeter.

Finding shorts and parasitic drains is not much fun. But there's no shortcuts I know of.

 

OK, RB83L69, thanks for the suggestion about the headlight motors, and the info that a draw from the items on the terminal board would not be revealed by pulling fuses. I remember seeing sparks under the driver's seat when I was checking out the motorized seat adjustment. Maybe the draw is in there.

Fortunately the battery takes about a month or so of sitting, in the car, hooked up, to get low enough to notice (which is strange since I have a draw big enough to light the test light). So I have the luxury of time, and I can still drive the car around to keep the battery charged while I check out the different things that might be causing the draw.

 

I know this sounds silly, but check to make sure all of your under dash lights are turning off also. I have seen alot of third gens have pennies in the cig lighter too.

 

Finally got around to putting a decent ammeter on the battery. I got the Advance Auto guys to test it on the 10 amp setting. It read only .01 amps, which is fine, right ?? So, I guess I have nothing to worry about. I guess .01 amps is enough to light up the test light. Wow, I spent a lot of time checking all sorts of stuff, but all I needed was a decent ammeter.... The battery will still get low if I leave the car sitting for about a month, though, probably, but apparently that's normal for a 3rd gen.

Oh well, a happy ending anyway

 

Well, I guess that's ok but it's still a drain. One last thing you could check is the starter. Unplug the connection going to starter and see if that is where your drain is coming from. i konw I fought with it for 3 freakin months before I figured out that was my problem. Sorry, I should restate that. It was 3 months........2 alternators.......2 optima batteries.......and 1 mini-starter later.

Hopefully your drain doesn't get worse.

 

Believe it or not but, a defective ECM can also cause a parasitic power drain.

 

But wait. Isn't .02 amps or less of parasitic drain "normal" ?