zoomjay

We have a 1998 ES300 that is randomly draining the battery. We have gone through the normal list of parasitic draws these cars have (stuck seat "set" switch; door lock actuator; broken switches; broken neutral switch; new battery cables; new starter; new alternator; new blower motor (old one was making noise) new battery) all to no avail - it still randomly drains the battery - and when it decides to do this - it can happen relatively quickly (sometimes less than 30 minutes). Once it kills the battery you can jump start it - it will run fine for several days and then randomly drain the battery (and the shop has no luck finding it).

Along the way my wife (who drives the car) has noticed that, from time to time, she hears a "buzzing" noise coming from behind the dash (center to driver side??). This past weekend after it killed the battery (and she had it jump started) she noticed that some of the warning lights on the dash came on and off. Specifically...

The yellow dash light showing a bad tail light came on, then went off; the light showing a battery warning came on, went off, came on, went off; the the yellow tail light light came back on and went off again... all within the scope of a 15 minute drive home. Oh yeah - the display on the radio is also bad - although I do not think this is related in any way.

I am wondering if these warning lights are associated with the buzzing which is means that some module behind the dash is going bad and is randomly killing the battery. If any of you have any ideas and/or suggestions please let me know.

Thank you

PuReChaos

Go buy a Digital multimeter (DMM), doesn't have to be expensive. Set it to amp and have the highest amperage allowed by the DMM, usually on cheaper ones its 10A. Car off. Disconnect your negative battery cable and stick one lead to the cable and the other to the terminal on the battery and look at what the amperage draw is. A good car does have a draw when the car is off, but it should be no more than 50mA. Start pulling fuses one at a time until you see your amperage reading on the DMM drop significantly. That helps locate what circuit could be causing the parasitic draw. You've already seem to have thrown some money at this problem, start with this so you can narrow down what is actually wrong opposed to just replacing items. I would be more than willing to assist you further after doing this test.

Should also mention there are plenty of youtube videos on how to perform this.

zoomjay

we (and my mechanic) have done this several times. Everything looks normal every time that we check it. We then drive the car for some time (few days, week, etc) and it does it again. Problem is that we have not been able to predict when it will happen - and it is intermittent.

If we could do the testing when it happens we would know.... although once it kills the battery it seems to "reset" itself and the problem goes away... a real head scratcher.

And yes, we have thrown much money at the problem going after the most "likely suspects"....

pauloil

take a look at the cable ends to be sure they are tight and have plastic on the bottom--I just helped a woman at work replace hers check your cables and grounds. google voltage drop test and read how to check battery cables. clean the contact points for your ground wires