I have a 94 SC400 and I have a parasitic drain on my battery. I have searched and it seems this is somewhat common among some sc's. With winter approaching I know I really need to correct this problem. Has anyone had this problem and found the cause of it?

I searched online to find a method to diagnose it and one method was to use a circuit tester and connect it to the negative battery post and the negative battery cable and if you had a parasitic drain the circuit tester would light up and then you have to go through each fuse one by one until the light on the circuit tester goes off to determine which circuit the drain is on.

 

had this on my old corolla....pain in the ***. yeah you can do the circuit tester thing.

just disconnect the negative terminal whenever youre gona be parked for more then a few minutes.

 

you should just go through your fuses, check your alternator fuse under your hood. then inspect your power, grounds, and alternator...

 

does your battery completely die and you have to recharge it all the time?

 

Lexus082, check your CD cartridge unit, the ejection button on my 95' stays illuminated and could be causing some of the battery drain. Invest in a Automatic Battery Float Charger, like the one below at Harbor Freight Tools.

http://www.harborfreight.com/cpi/cta...emnumber=42292

 

Watch out for the radio. That is the current problem that mine has right now, too. The radio's fuse had to be disconnected because it would totally drain the battery.

 

I have had a slow drain on my battery going for sometime now..but just recently my dash lights have been staying on from time to time..put a ground kit on the other day, seems to have cleared it up.

 

another option is to fish out a voltmeter and check the drain on the battery voltage while you pull out each fuse. Hook up the voltmeter and let it sit for a minute or two so you can see the battery voltage drop over time. Then start pulling fuses, checking each time to see if the circuit is the cause of the drain. Once you see a significant drop in voltage drain you have found your circuit. Then you have the fun job of finding out the problem in the circuit. Good luck!

 

The test light trick only works with some test lights. Dont really know what it is, probably the light bulb some of them use, but not all of them will work.

Most of the time the drain is from the radio or a light that stays on.

 

My battery doesn't completely die every time I turn the car off. But something is definately draining the battery when its not running. I can rule out the cd changer because I removed mine a long time ago, so I know its not the changer. The only light I have yet to check to make sure it doesn't stay on is the trunk light. Looks like I will use the multimeter instead of the circuit tester. Can't wait to get this resolved.. Atleast the drain on the battery isn't any stronger to where I would have to jump it on a daily basis.

Aren't you suppose to measure the amps instead of the volts when performing that proceedure StiCk3?

 

I have seen both methods at work and both work the same. I'm used to the volts reading only when diagnosing a parasitic draw. Amp draw can work as well, just remember to hook up amps in series, not parallel!!

 

Well I asked the mechanic at work and he said the same thing about measuring the voltage in amps and volts. He recommended going off the volt reading. So I did what he told me to do and disconnected either the positive or negative cable from the battery. He said it really didn't matter, either one would work.

So I connected the positive lead from the volt meter to the positive battery terminal and then the negative lead from the volt meter to the positive battery cable to get a voltage readout. I believe this readout would indicate if there was an abnormal parasitic drain on the battery. He said the readout should either be "zero" or approx. 12 volts.

According to the mechanic, a readout of "0" meant there was no drain (normal) and a 12 volt readout would indicate there was a abnormal drain present within the electrical system.

My multimeter displayed 10.5 volts and I went through trial and error with each fuse to find the circuit the drain was on. Removed all the fuses and the 10.5 reading never changed. The mechanic said it shouldn't read 10.5 and said I might have a bad battery. So before I go any further I'm going to have the battery tested. Its a Lexus battery and its only 3 years old (84 month warranty).

 

yeah 10.5 for a 12v battery is bad. You can try charging it separately. Charge it, then check the fluid level of the battery under the little pop off caps, in that order (unless its a sealed battery). If its low, if you can see the lead plates, then add water.

 

With mine it was the trunk light

 

Had the battery tested tonight and in the first test it tested good, but the number of cold cranking amps was really abnormally high at 1700. That test was done right after a ten minute drive. Then the second test... 1st test the battery voltage was 12.6 and the 2nd test the battery voltage had dropped to 10.5 within 5 minutes and it tested bad. Apparently the battery has a dead cell and its defective. So theres no parasitic drain.