After having battery and alternator checked to be good I discovered a draw on the battery . With an amp meter on the positive cable leading to the fuse panel the needle would jump intermittentlyto about a 5 amp (spike) then to zero, this continued until the battery was dead. After pulling each fuse 1 by 1 the culprit was fuse location # 8 a 20 amp fuse that controls the rear electronic module among other things. I would like to repair this problem myself if possible. If the module is at fault where is it and what can I expect to pay for it. Thanks in advance.
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Re: draw on battery
Have you had any recent electrical work done, including installs of new radio, bulbs, amplifiers or the such. Something is running when it shouldn't be, obviously, but what? The easiest way to go through this with fewest headaches is to start pulling fuses and taking readings to determine if that circuit has the draw. At least this will narrow down the list of culprit. You sound like a pretty sharp guy, I'll let you take it from here.
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The only way to solve this problem is to isolate which circuit is causing the problem. To do this you must have an amp meter. (one that will read up to 10 amps minimum; I doubt you are drawing more than that) With key off, disconnect the positive cable to the battery and insert amp meter, positive meter cable to positive terminal and negative meter cable to positive cable on car. Normal draw will be in the milliamps. Anything 1/4 amp or more I would consider abnormal. Then star removing fuses (one at a time) until drain disappears.
You will need to check for a draw on the system. you will need a volt meter that can measure amperage. Remove the positive battery cable from the battery. With the volt meter set to measure amperage place one lead on the positive battery post and the other lead on the positive battery cable. If you see more than .050 amps you have a draw. I would suspect that you have closer to .500 amp for the battery to go dead overnight.
Sounds like you have a draw in your electrical system. You will need a multi meter capable of measuring amperage. With the key out of the ignition, and the doors closed disconnect the positive cable from the battery. Hook one lead of your meter to the positive post of the battery. Place the other lead on the positive cable end. You should see less than .050 amps. Anything more and you have a draw. You will then need to pull fuses one at a time until the draw goes away. Then you can focus on that circuit to see what is causing the problem. Typically aftermarket radios, glove box lights, heated seats, and vanity lights are pretty common sources of draws. Let me know what you find and I'll see if I can't help you further.
I would start by checking for draws. You can do this with a DVOM capable of reading amperage or with a low amp probe.
With a volt meter set the meter to the 10 am range. Remove the positive cable from the battery. Hook one lead of the meter to the positive battery post and the other to the positive cable end. You should see less than .050 amps of draw and better yet at least half of that.
If you see more you will need to start pulling fuses to see which one makes the draw go away and then focus on that circuit.
Btw, always post a Year, make, model, and engine size with any automotive related question.
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If you don't have any idea what to check next, maybe now is the time to take the vehicle to an auto electric repair shop that specializes in tracing wires. You may have a short to ground somewhere, or an accessory, that is drawing current when the vehicle is off, to the point of making the battery go dead if sitting more than 15 hours.
One check that you could do yourself, with the proper tool, is to check the amps being drawn when the car is off. If the amps drawn is above .2 Amps, then it's too high of a draw. The symptoms you describe sound like it is more like 2 or 3 (or more) Amps being drawn on the battery.
Try to remove fuses to various accessories to see if that reduces the amp draw on the amp meter.
I would use an Amp meter that is inductive and has a claw that opens and surrounds the positive or negative battery cable and measures current without having to actually remove any cables from the battery, and connect in between the battery terminal and the battery cable.
Let's say, for instance, that it was an accessory like a radio that was drawing an inordinant amount of electrical current. Then, if you removed the radio fuse, the draw should go from 2 or 3 amps down to below 0.2 amps. So, that's what I would do to try to narrow down the possibilities.
Check for consumers staying on such as interior lights , radio etc.. To check for current draw, you need an AMP meter. remove the negative battery terminal. Connect one amp meter lead to the battery negative terminal and the other to the earth cable. Hold the cable against the battery negative cable, close all doors and press bonnet switch to closed position. Activate the alarm and wait for it to arm. Once it has armed itself, separate the earth cable from the battery terminal keeping the amp meter connected. read the current draw. Should be less then 100 milli amps. Usually +- 40ma. To check which circuit has current draw remove one fuse at a time and check if current draw drops. A drop in current draw will indicate that the problem is on that fuses circuit. Also check alternator charge rate. To check this hold a volt meter across the battery terminals. with engine off, should get battery voltage. Start the vehicle, battery voltage should rise to 13 -14v and maintain this voltage with the headlights on. The battery itself could be faulty, you would need to do a load test on the battery. Load tester needed to do this.
Make sure battery posts and cables are clean and tight, same thing for connections at the alternator and starter. Use a voltmeter to test for parasitic draw. Attach meter between positive post and positive cable (cable disconnected), with meter set on amps, and pull fuses one by one until you locate the circuit.