'93 Cherokee electrical drain, no luck tracing fused circuits.

Hi all, I've got a '93 Cherokee Country, and when I stick my multimeter between the negative battery post and the negative terminal with the doors shut and the ignition off, I still read voltage as if checking terminal to terminal.

I pulled each fuse and each relay one at a time from the box in the engine compartment as well as the fusebox beneath the driver's seat to the left, and the bank of relays to the right. I still read voltage. In my typical vehicles I should see no voltage because there should be no circuits functional, and there should be no draw on the battery.

Is there something funny about these things (just got it), or do I have some funky electrical problem that's going to leave me with a dead battery come winter if I don't drive the car every day?

Thanks,
-Josh

tapher said:

when I stick my multimeter between the negative battery post and the negative terminal with the doors shut and the ignition off, I still read voltage as if checking terminal to terminal.

Click to expand...

Josh,

Could you explain this more clearly.

Well, voltage is OK. What you want to check for is DRAW--amps or miliamps to be more precise.

While you can do this job with a multimeter, I'm old school and prefer a 12 volt test light because it is simple and VISUAL.

When you hook up a 12 volt test light in series with the battery and the negative cable end, IF the light glows DIMLY the draw is normal (PCM, radio presets, etc.). If the test light lights up fully, THEN you have an excessive draw that will kill your battery.

You can do the same things with a multimeter that has a AMP test circuit, usually limited to 10 amps and less, but then you have to keep checking the meter when you are pulling fuses or disconnecting components, the the 12 volt test light you just need to see the light go dim or off.

Good luck.

PS--your draw should be at or below 50 mA.

Sidewinder CC,

I mean to say that I've disconnected the negative battery cable from the battery post. I would place the multimeter between the two, in effect temporarily closing the circuit.

Joe Peters, I'd've used a test light, but the battery was quite dead. Is it really true that reading a voltage is normal? I had always thought that no amp draw whatsoever should take place on a battery in a car that's not running with the ignition off and the doors closed and stuff. Please elaborate, and others feel free to comment.

Thanks!

-josh

The 95 FSM says normal ignition-off draw for a Cherokee should be something around 20 milliamps (radio, clock, PCU, etc.). It might be a little more if you have keyless entry, an alarm or a non-factory radio. That's quite enough to register on any but the most primitive voltmeter, so you really need to read the current with an ammeter to find any problems here.

I agree with the current vs. voltage part as Joe and Matthew have suggested already. Anyone who doesn't is ignoring a lot of expertise. If you really want to study this on your vehicle, take out ALL the fuses first, then add them in one at a time to see if the things you expect to draw current actually do. Radio memory, PCM, etc.

I am not sure if a 93 is the same as my 91 Limited but I experienced a similar problem quite some time ago. It would be fine with a newer battery but after a few years, it wouldn't start after a few days. It got to where I would disconnect my battery at the airport to make sure I didnt need a jump. I tried all the current draw tests and disconnected the aftermarket alarm, radio, amp, etc to no avail. I did notice that it had the yellow "security" light on the left side of the dash that would come on and off without any real rhyme or reason. I searched online, maybe even here, and found that there was a factory alarm module, hidden way up in the top of the dash. It has a very specific method of removal to make sure that you don't lock out your ECM. I forget what it was but you have to make preparations before you disconnect it. Once I did that, my drain problem was gone. I would be interested in learning if this is your problem or if others have experienced the same issue.

JohnnyTurbo, this may well be the problem as I tried the swap-in of a new battery (the old one was officially toast) after finding no funny amp draws (thanks for the thoughts, everybody!).

I don't have the wiring diagram for the vehicle, but it could make sense that an alarm system could be the vampire secretly stealing amps. I'll see if I can't google some info on the alarm system and will share what I find!

Thanks!