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winddance@att.n 12-08-2003 12:16 PM

Short draining battery
My battery goes dead after a week or 2 of not driving. I pulled the cable and put an ohm meter on. It showed 2 things (after pulling the radio fuse, of course). 1) With the fuse for the cig lighter/dome light etc., pulled my meter shows 163 ohms resistance. I imagine that is for the computer or something. That isn't enough to drain the battery, is it? 2) The system shows a complete circuit with the cig lighter fuse in. This sounds like whats draining the battery. Anyone out there have a similar problem with that circuit? Be nice to have a starting place, rather than going over every one of the circuits connected to that fuse. Oh, I tried pulling each fuse one by one and the 163 ohms stayed there the whole time - as long as the cig lighter fuse was pulled, of course. Thanks!

SoCal Driver 12-08-2003 02:08 PM

What year and model?

More than just the lighter is on that circuit. PO or radio installer could have tapped it for the antenna or second power amp.

winddance@att.n 12-08-2003 02:26 PM

'86 944. Yep if I remember correctly it is the lighter, glove box light, dome light. Thought about the radio antenna booster, it is on another circuit - original antenna in windshield. No amp that I am aware of. Original radio. Thanks!

adrian jaye 12-08-2003 11:57 PM

a better tests would be below.

use a DVM, disconnect the neg lead and put in series with the battery, set to amps. current drain should be between 10-80 mA.

try same test with pulling fuses, circuit that lowers the current is the culprit.

usually it is the interior ligghts/glove/hood/trunk
radio amp is connected to permanet feed. (look at aerial lead is there a power tag connected to it.

anything happen to the car before ?

holla back


winddance@att.n 12-09-2003 04:52 AM

Been there, done that per previous posts.

cruzermusic 12-09-2003 06:43 PM

if your checking for resistance in the connection you would use the ohm setting on your meter...resistance on good connections should be almost 0, depending on the lenght of the ie; wire size, tight connections etc..

if your checking voltage...use dc volt setting...hook up to the battery..and watch the voltage,,if it drops , have a drain somewhere..something going to ground??...start you car and see if your getting 14+ volts charging....if not the discharge might be your alternator or voltage regulator.....

the next thing that solves most problems is the amp meter....set your meter to the amp setting and you can find any circuit ,wire,switch,etc, thats pulling power when its not supposed too...

turbohead7 12-10-2003 04:16 PM

Slow drain
Dude, using your ohm meter in that way won't help anyone, including the car and the meter. First off, make sure the battery is good. Now, get out your AMP METER (for measuring current) and prepare to hook it between the negative post and the cable. There are two things you must do to get an accurate draw reading: 1)Cycle the key and open/close the door prior to disconnecting the battery. This energizes all the relays/computers/circuits in the car briefly, and only the ones designed to stay on should. Everybody forgets this f@^$#(* step. Remember, you are trying to locate a component which is "sticking" on----you need to energize it first. Oh, and for all you that are wondering, opening and closing the door after the key cycle kills the power window relay which stays active until you open the door, the door switch shuts it off. 2)MOST IMPORTANT: when hooking up the amp meter don't lose the battery connection!!! If you do you just shutdown every component in the car and must repeat step#1. Start your amp meter on the high or 10 amp scale. If it reads 0 or .02, hook up the cable and switch to the low scale or 300mA sacle. 100mA is a tenth of an amp, so half an amp is 500mA which is a lot. A light bulb draws over one amp, a relay is usually 200mA+. You should see no more than 25mA, depending on aftermarket accessories. If more, have an assistant hold your connection, and start to pull fuses and relays. If less than 100mA, start with fuses, if over 200mA, start with relays. And please, never ohm out your battery like that again.

cruzermusic 12-10-2003 05:00 PM

well,, a person who has seen a meter blow up via a wrong connection...thanks for the door/key thing..makes sence to i see it linked to my car alarm,,and other would be nice to go back to the pre-computer stuff for the car to run.....but u pay for performance....

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