Amp / Voltage draw issue.

[robbz28]

I have a problem and I wanted to just throw this out there before I break my multi-meter out and start poking around on the car. I have something, somewhere sucking the life out of my battery over the course of a week. I thought maybe I had a bad battery, took it to Autozone today and they tested it and said all's well. So are there any "usual suspects" as far as these cars go with this issue? I know my dome lights, under-hood lights, courtesey lights, and glove box lights are in working order. The radio is stock, but there is an aftermarket amplifer wired in to replace the bose speakers, but the power light on it is off when the car is. Maybe a stuck relay or something?? Where to start? What to do? My little 1.5 amp battery charger stays on it in the meantime.

[-=Jeff=-]

my best suggestion is to connect the multi-meter and pull one fuse at time and watch the current level..

but before that.. what was the last thing done to the car prior to this occurring?

[GOLDCYLON]

Check the map lights in the visor as well. Is this a combo top and side post battery you have? G C

[secondchance]

Check and make sure door switch for courtesy light is working - shutting off after 15-20 seconds. These switches has been known to go bad.

[robbz28]

Its been like this since i got the car...it sits for longer than a week and it needs a charge. I have had the car for about 6 weeks. It is a side post battery and the lights do turn off. The visor lights are off as well.

[-=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?

[ghlkal]

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]

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.

[robbz28]

I plan on measuring and testing...looks like i have something to do this weekend...

[WVZR-1]

Originally Posted by robbz28

I plan on measuring and testing...looks like i have something to do this weekend...

I'd maybe ask someone with a '91MY to check theirs for a good reference for the basic test. That might give you a "target"! If you go to a FSM it will ask you to add circuits to arrive at a value. A known good starting point might be my best thought of the day!