Electrical Problem in 95

Hi,

Hope some of you can give me some ideas to pass onto my mechanic, since he seems to be out of ideas. The only problem I have ever had with this car seems to be an intermittent electrical problem. Electrical system checks out fine, but the battery keeps going dead on me. I've replaced the battery a couple of times, and each time it seems to work for awhile, and then I get the same problem. This last time the alternator tested as bad. I had it replaced to the tune of $200. Seemed okay for a short while, but then started doing the same thing. Electrical system checked out fine again, battery fine. On a hunch my husband had the mechanic replace the ignition switch. I thought finally my problem was solved. Now it sits out in the drive way with...you guessed it...a dead battery again! I can't afford to keep guessing what's wrong with it. I don't blame the mechanic, he's good at what he does but we must be missing something. Next thing suggested is a brain box (?) which is expensive new. Is that a possibility? I'd appreciate any suggestions.
Thank you.

The actual "brain" is not bad within itself it sounds like your module is not "sleeping". What that means is that after you have shut the engine off, there is a very miniscule drain on the battery to maintain the memory of the clock, radio, engine operating parameters, etc. If the module drains too much juice, it will drain your battery over a 4 to 5 hour period. Excessive drain can be the equivalent to leaving your lights on. Tell your mechanic to test the Powertrain Control Module and see if it is drawing too much current. If you can remember, tell him that the accepted limits of a module draining the battery is 200 milliamps.

Thanks for the reply. I will pass that info onto my mechanic. It makes sense to me!

To add to the mystery, we took the battery back after testing it with a hydrometer that showed it was bad. Place I bought it said battery was good, but if we brought the car in they would do an electrical test, and if they didn't find any problems with the electrical system they would replace the battery. This is only like the dozenth time its had an electrical check....anyway. Everything checked out, and they agreed to replace the battery BUT the new alternator (bought at the same place) is pumping out 140 amps when it should only be putting out 90 amps. So now it sounds like I have to replace the alternator again!

Yeah, it is definitely your Powertrain Control Module. That module controls alternator output. If it is pumping out 140 amps, it's overcharging and will start smoking things like other modules, and other sensitive, low-current circuits. Get that replaced as soon as possible. The only downside to that is that the Powertrain Control Module is not cheap, like around the $900 range. Just a little FYI so you know.

Thanks again. My mechanic is looking for a control module at the wrecking yards. $900 is a little beyond my budget at the moment.

I had a similar problem with my 1993 Intrepid. Took it to a battery and electrical "specialist" who could not detect any significant drain on my battery. The alternator was okay as well, but on most mornings my battery was dead. Not just drained, but completely dead. In many ways, this sounds like your problem.

The problem was in a relay. The air conditioning relay was sticking on. My father could hear a faint clicking sound coming from the relay/fuse control box under the hood, and we quickly figured out which particular relay was the culprit. For about $10, we solved the problem.

I don't know what the heck is going on. Haven't done anything to it since my last post, and it has been starting everyday. But give it six months and the problem will likely return.This has happened several times before, and after replacing the battery it would be okay for awhile.

Yeah, my battery was totally drained too. Usually after eight hours which means dead in the morning and dead when I get off work. I'll get this relay switch you mentioned checked,and then find a control module for it if that isn't. Thanks for the suggestion.