Before the winter I had a problem with the battery in my 98 going dead after a couple of days of non-use. I just uncovered the car after the winter, and found that the battery wouldn't take a charge. No surprise, since I had left it dead through months of freezing temps.

I bought a new battery, & just did a static battery current draw test. The current draw quickly settles at about 3.25 amps. (!) I watched it for about 15 minutes, then disconnected everything to come do some research.

From what I read here, common problems include something in the power seat control, the Bose amplifier, and the headlamp control module.

I see references to fuses for the seat & the Bose amplifier, but not for the headlamp control module. Is there a fuse I can pull to see if the headlamp module is the culprit?

I also see suggestions to feel the headlamp module to see if it's warm, or to disconnect it & see if the current draw drops, but I have no idea where the module is. Can I get to it from under the hood?

Thanks!

 

Here is some info for determining if you have a parasitic drain. Let me know if I need to clarify anything of if I can help in any way.

Suggest you remove the hood light bulb first so it does not provide a drain.

For measuring battery drain I would hook up an ammeter to the negative side of the battery by removing the negative cable and measure between the cable and the negative battery post.

When you connect the ammeter the car should draw several amps until it goes into "sleep" mode which can take several minutes. Normal sleep mode drain should be between 17-22 milliamps. You will need an ammeter that can transition from whatever the drain is down into the sleep mode. If you have a drain I suggest the following:

Once you determine you have a drain with an ammeter what I recommend first is to listen to each fuse box and see if you hear any relays operating. If not, then place your hand on each relay to see if any of them feel hot. That can be the start if you find something like that is happening.

If nothing shows up you can hear or feel then I recommend you separate the two fuse boxes from each other. This is easy and done by removing the Red cable from the engine fuse box that feeds the passenger fuse box. It is on the right rear side of the engine fuse box. There is a stud there where the large Red wire from the battery connects. Just remove the nut and disconnect the large Red wire feeding the passenger fuse box and reattach the Red battery cable. NOTE: I would recommend disconnecting the negative ammeter hookup when working on the positive side doing this.

What you will be doing is measuring the drain with an ammeter to see if disconnecting the passenger fuse box causes the drain to go away or not. By depowering the passenger fuse box you will depower the BCM which controls the sleep mode so do not expect the sleep mode to happen.

If removing the feed to the passenger fuse box you then see you have eliminated the drain then you know it is something related to those circuits. If it does not reduce the drain then you know it is related to the engine fuse box. It could be a rare case where you have some drain via both fuse boxes and we can deal with that if you think it is the case.

Once you basically know where it is then you can remove fuses and relays to see where the drain is coming from.

PS: There are cases where the alternator causes a drain so it can be disconnected and see if the drain drops.

 

Thank you for the response, dadaroo. I like the idea of electrically separating the fuse boxes; I hadn't thought of that.

I did remove the under hood light bulb before I started messing with this yesterday, and ensured that all other lights were turned off, doors closed, etc.

I had left the battery disconnected & on a charger for many hours last night, so went out to start pulling fuses or whatever this morning. I hooked up my meter (same way you suggested) and found that my current draw is now 30 milliamps. Big difference from the 3.25 AMPS I saw yesterday. So maybe I have an intermittent problem?

I then reconnected the battery, ran the car for a while, then disconnected the battery & rechecked the current draw. Still 30 milliamps. One thing I did notice, which may or may not be significant, is that I did NOT get an initial high current surge when I connected my meter. It immediately read 30 milliamps & stayed there. Does this indicate anything specific?

I need to go out this morning & get some electrical clamps to make it easier to hook up my meter to do the current testing. Then I guess I'll try the current test each time I drive the car & see if I can catch it in the high drain mode so I can try & isolate the problem.

Thanks again for your suggestions, & please let me know if you have any other thoughts. I'll post again after I do some further testing.

 

Normally when you reconnect the battery during drain testing you should expect several amps until the BCM goes into sleep mode. Can't explain what you saw. 30 milliamps is still a little high but not bad.

If you feel the need to discuss anything just PM me with your number and we can talk. Much more effective in exchanging ideas and info.

Mr. Sam

PS: Separating the Battery feed to the I/P fuse box does not completely separate all the circuits between the 2 fuse boxes but it can/should tell us big picture where to look. Using the schematics I can help you find the issue.

Remember we need to know what year your car is as a minimum since wiring differs between years in many areas.