Mystery Voltage Draw - ZR-1 Net Registry Forums

Bob Eyres · 07-23-2015

We are trying to cure a long time problem with my ZR-1.
I find that if I don't keep a battery minder, or low voltage charger, on the car it will draw a fresh battery dead in 3-4 days.

I've got a friend with a voltage tester, and he says it's got about a 3 amp draw on the battery at rest with nothing turned on.
That seems like a lot. In fact it should be about what?... a half amp if nothing's wrong?
We don't have the ZR-1 electrical manual to refer to. So I'm wondering if you guys have run into this problem in the past, and what was the solution.

I know it could be a number of different things, but I'm trying to find the most common solutions, to narrow down the search.

TIA

GOLDCYLON · 07-23-2015

Quote:

Originally Posted by Bob Eyres

We are trying to cure a long time problem with my ZR-1.
I find that if I don't keep a battery minder, or low voltage charger, on the car it will draw a fresh battery dead in 3-4 days.

I've got a friend with a voltage tester, and he says it's got about a 3 amp draw on the battery at rest with nothing turned on.
That seems like a lot. In fact it should be about what?... a half amp if nothing's wrong?
We don't have the ZR-1 electrical manual to refer to. So I'm wondering if you guys have run into this problem in the past, and what was the solution.

I know it could be a number of different things, but I'm trying to find the most common solutions, to narrow down the search.

TIA

Do you have a side and top post battery ?

Make sure your mirror lights are off.... the ones in the sunvisors.

Jagdpanzer · 07-23-2015

Should be less than 20 milliamps with eveything off, key removed so CCM goes fully asleep. With this small amount of drain a good battery should last for weeks.

WVZR-1 · 07-23-2015

What year is the car? I believe the newer cars with the under-hood fuse boxes are likely much easier to trouble shoot. Is there any added accessories? After-market radio or alarm etc.

Eliminate the most likely by removing the connector to the H/L module and disconnect the H/L motors AFTER you've walked around the car with the doors closed and the lights out in the garage, if it's an earlier year check the spare tire light.

secondchance · 07-23-2015

I had a similar situation with battery going flat in a day or two. In my case it turned out to be HVAC fan controller gone bad. Even with the ignition turned off the controller was running the fan at very low speed. Not saying your cause would be the same but worth checking out.

Marc Haibeck · 07-24-2015

I encountered a car that drew about 60 ma all of the time. It would drain the battery in about two weeks. The current draw was on the ABS power line. I eventually found a LoJack system, including a back-up battery for the LoJack, under the black panel under the rear of the hatch glass.

Bob Eyres · 07-24-2015

Thanks guys, I'll check this stuff out. The car is a 91' with no non-stock electrical accessories, Lo-Jack etc.
We thought it might be the headlight motors, but after replacing the gears and re-assembling, it's still pulling 3A. I'll let you know how it shakes out, and if anyone has other ideas, feel free to post.
Thanks.

Bob Eyres · 07-24-2015

Quote:

Originally Posted by GOLDCYLON

Do you have a side and top post battery ?

Make sure your mirror lights are off.... the ones in the sunvisors.

Nope, Delco side post only. I'll check those visors. That would be an easy fix

thanks

-=Jeff=- · 07-24-2015

My buddy had a similar issue with a 1992 Thunderbird

We used a DMM set for current and connected in series on the positive post to the positive cable.

Then we started pulling fuses and watched the current looking for the drop off.

If you had the FSM you could narrow it down further by just looking for the 'always' hot connections..

Maybe check the door chime module? I think I have heard that causing issues ( just don't remember where I heard that)

GOLDCYLON · 07-24-2015

Quote:

Originally Posted by Bob Eyres

Nope, Delco side post only. I'll check those visors. That would be an easy fix

thanks

Bob don't forget pull it into a dark garage to make sure all the lights are off as WV suggested. You might have a duff door switch or rear hatch switch leaving the lights on including the spare tire light as well. GC

07-23-2015	#1
Bob Eyres Join Date: Jul 2005 Location: Jupiter, Fl. Posts: 815	Mystery Voltage Draw We are trying to cure a long time problem with my ZR-1. I find that if I don't keep a battery minder, or low voltage charger, on the car it will draw a fresh battery dead in 3-4 days. I've got a friend with a voltage tester, and he says it's got about a 3 amp draw on the battery at rest with nothing turned on. That seems like a lot. In fact it should be about what?... a half amp if nothing's wrong? We don't have the ZR-1 electrical manual to refer to. So I'm wondering if you guys have run into this problem in the past, and what was the solution. I know it could be a number of different things, but I'm trying to find the most common solutions, to narrow down the search. TIA

07-23-2015	#3
Jagdpanzer Join Date: Apr 2007 Location: Northern VA Posts: 2,661	Re: Mystery Voltage Draw Should be less than 20 milliamps with eveything off, key removed so CCM goes fully asleep. With this small amount of drain a good battery should last for weeks. __________________ Phil Wasinger 1994 Torch Red ZR-1 WAZOO Member George Braml Intake

07-23-2015	#4
WVZR-1 Join Date: Oct 2004 Posts: 1,890	Re: Mystery Voltage Draw What year is the car? I believe the newer cars with the under-hood fuse boxes are likely much easier to trouble shoot. Is there any added accessories? After-market radio or alarm etc. Eliminate the most likely by removing the connector to the H/L module and disconnect the H/L motors AFTER you've walked around the car with the doors closed and the lights out in the garage, if it's an earlier year check the spare tire light.

07-23-2015	#5
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,723	Re: Mystery Voltage Draw I had a similar situation with battery going flat in a day or two. In my case it turned out to be HVAC fan controller gone bad. Even with the ignition turned off the controller was running the fan at very low speed. Not saying your cause would be the same but worth checking out.

07-24-2015	#6
Marc Haibeck Join Date: May 2007 Location: Addison IL Posts: 250	Re: Mystery Voltage Draw I encountered a car that drew about 60 ma all of the time. It would drain the battery in about two weeks. The current draw was on the ABS power line. I eventually found a LoJack system, including a back-up battery for the LoJack, under the black panel under the rear of the hatch glass.

07-24-2015	#7
Bob Eyres Join Date: Jul 2005 Location: Jupiter, Fl. Posts: 815	Re: Mystery Voltage Draw Thanks guys, I'll check this stuff out. The car is a 91' with no non-stock electrical accessories, Lo-Jack etc. We thought it might be the headlight motors, but after replacing the gears and re-assembling, it's still pulling 3A. I'll let you know how it shakes out, and if anyone has other ideas, feel free to post. Thanks.

07-24-2015	#9
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,169	Re: Mystery Voltage Draw My buddy had a similar issue with a 1992 Thunderbird We used a DMM set for current and connected in series on the positive post to the positive cable. Then we started pulling fuses and watched the current looking for the drop off. If you had the FSM you could narrow it down further by just looking for the 'always' hot connections.. Maybe check the door chime module? I think I have heard that causing issues ( just don't remember where I heard that) __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978