Amp / Voltage draw issue. - ZR-1 Net Registry Forums

-=Jeff=- · 10-16-2012

Next I would suggest disconnecting the Stereo aftermarket amp and see if that fixes it..

Is there an aftermarket keyless entry or alarm on it?

ghlkal · 10-16-2012

Quote:

Originally Posted by -=Jeff=-

Next I would suggest disconnecting the Stereo aftermarket amp and see if that fixes it..

Is there an aftermarket keyless entry or alarm on it?

These are both good suggestions. On my 85, it came with a bunch of stereo stuff. Even with it all shut down, it was still pulling power and would drain the battery until I finally pulled all of it out.

On my Z, the PO put in an aftermarket alarm system. What a PITA. It will suck the battery down after a week. It's on my list of things to pull out this winter.

WVZR-1 · 10-16-2012

I agree with -=Jeff=- but first establish what the simple parasitic draw actually is. Do you have a DVM? Set your DVM to either 10A or 20A and with the DVM connected between the negative terminal of the battery and the negative cable see what it actually is. Make sure the car has "gone to sleep" - "key off" or in your pocket. If you've got something very low maybe 30 milliamps or less it says maybe you don't. An early 90's car you might expect maybe as little as 20 milliamps or so to be the norm. Never checked mine.

If you've got something larger than that could be as high as 2 - 3 Amp or so you then start to pull fuses one at a time and monitor the drop. When you pull one that dramatically lowers the draw to an expected value then you search that circuit. I was always told to pull lower amp fuses first (don't know why) and do larger value and breakers last.

I was also told to do this first but don't remember ever doing it. Remove both battery cables and check Ohms across the battery cable ends. Something very low hints major shorts.

I don't recall how easy the red wire is to get to on the alternator but a bad diode will take a battery down pretty quick. You could remove it to check also.

It's much easier for me to walk to the car and do it than it is to try and explain it but I just wouldn't start tearing into things. I'd measure the drain before I even worried about the amp. I might make the amp first after the check though.

10-16-2012	#1
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,163	Re: Amp / Voltage draw issue. Next I would suggest disconnecting the Stereo aftermarket amp and see if that fixes it.. Is there an aftermarket keyless entry or alarm on it? __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Shelby Series 1 - Wilwood Brakes Custom Interior NCM Lifetime Member #978

10-16-2012	#3
WVZR-1 Join Date: Oct 2004 Posts: 1,884	Re: Amp / Voltage draw issue. I agree with -=Jeff=- but first establish what the simple parasitic draw actually is. Do you have a DVM? Set your DVM to either 10A or 20A and with the DVM connected between the negative terminal of the battery and the negative cable see what it actually is. Make sure the car has "gone to sleep" - "key off" or in your pocket. If you've got something very low maybe 30 milliamps or less it says maybe you don't. An early 90's car you might expect maybe as little as 20 milliamps or so to be the norm. Never checked mine. If you've got something larger than that could be as high as 2 - 3 Amp or so you then start to pull fuses one at a time and monitor the drop. When you pull one that dramatically lowers the draw to an expected value then you search that circuit. I was always told to pull lower amp fuses first (don't know why) and do larger value and breakers last. I was also told to do this first but don't remember ever doing it. Remove both battery cables and check Ohms across the battery cable ends. Something very low hints major shorts. I don't recall how easy the red wire is to get to on the alternator but a bad diode will take a battery down pretty quick. You could remove it to check also. It's much easier for me to walk to the car and do it than it is to try and explain it but I just wouldn't start tearing into things. I'd measure the drain before I even worried about the amp. I might make the amp first after the check though. Last edited by WVZR-1; 10-16-2012 at 09:55 PM.