High Parasitic Battery Drain on a 1999 Avalon XLS - Toyota Nation Forum : Toyota Car and Truck Forums

edge10 · 01-06-2012, 01:56 PM

I trying to find the cause of high parasitic battery drain on a 1999 Avalon XLS Platium Ed. According to the service records this has been a problem since new, so it could point to a common defect rather than a part wear out. So, I'd like to know if there are any typical failure problems at the part level to help narrow it down from the circuit level. One I did find is that Avalons may have a problem with the stereo amp which does not switch off and draws current.

After bringing the battery to a full state of charge 12.7 V the battery will drop to about 12.3 V after 24 hrs and nearly dead at 11.9V 5 days without driving. No problem with the any interior or trunk lamps. I plan to check each circuit pulling fuses and then the alternator to find the bad circuit by checking the parasitic draw at the neg battery cable.

OpticNerve · 03-25-2012, 12:07 AM

Any luck what might be causing the drain? My son has a 09 Tacoma that is going dead on him. It might be just a dead cell in the battery, but I have know the Johnson Control batteries in the Toyota's to go much more then 3 years. Have you found anything?

***TrailDust*** · 03-25-2012, 01:31 AM

To the OP, the best place to start is with your battery connections. Inspect the cables and the connectors themselves, and also make sure the connections are tight. I encountered a situation once where I thought it was parasitic draw, but turned out to be a loose connection at the negative terminal that allowed arcing to drain the battery in as little as 24 hours. If all your connection are good then have the battery tested. Once all that is done and the draw/drain persists, then take it to the next level and hook your electrical system up for an overnight attempt to find the source of the draw.

edge10 · 03-25-2012, 11:59 AM

Here what I have so far. The battery pos terminal to case voltage was checked out OK on the old battery ( had this type of drain on another car at one time). However, the battery was unable to take a load and was defective after two years. It was replaced under warranty. So, this part of the problem.

I measured the drain with the new battery at a full state of charge and found it was .03 A, which is just within the upper limit generic Toyota spec. I am not sure if this is within the Avalon spec. The 0.03 A drain remained when I pulled all the fuses in the fuse block except the SRS airbag.

I have not check a wiring diagram yet. If the current drain is out of spec it could be a stereo amp with is fused separately from the fuse block which I read about or the alternator, SRS or ECM. But like I say it was like this since new.

OpticNerve · 03-25-2012, 08:12 PM

TrailDust and Edge10 thank you both for the inputs. Will text my son on what he could do to find out what is up with his 09 Tacoma battery. If my math is correct, .03 Amps equals 30 milliamps. For those interested, I found a good video from EricTheCarGuy.com at

You Tube

. His suggestion was that anything under 50 milliamps is an acceptable battery drain after everything electronic has gone to sleep. I had a 2000 Avalon with 160K up until last Feb 2011. Edge, I believe your car has low mileage for it's age from one of your earlier postings. It is still around 14 NJ years old, and must have a degree of resistence all over the electrical place. If you ever have any DTC's that point to the oil control valves(vvti), MAF, A/F or 02 sensors, send me a PM.

I love these forums.