DangerBoy

Hi Everybody,

I just joined and this is my first post.

As the headline states I have an '02 4Runner SR5 with only 130,000 km (~75 Kmiles) on it. It is pretty much all stock except the 3rd party tail lamps I put on it.

I've got a parasitic drain problem that's perplexing me. Whenever I leave the vehicle parked for 2-3 days the battery will go dead. I just purchased the battery a couple years ago. It's a 1000 Amp battery and seems to hold a charge fine if I am using the vehicle regularly.

I just went out and did some troubleshooting on the truck and this is what I encountered. When placing a multi-meter between the negative battery post and the the negative battery lead I read about 0.04 amps draw with the headlamp switch off and no key in the ignition.

I did a test where I pulled each fuse out one at a time and measured the current across the fuse contacts and only found 0.009 amps going across one of the fuses. The rest were 0. It should be noted, however, these were only the mini fuses that I tested. I was unable to pull the other bigger fuses, not having a puller for them.

I then checked the draw between the negative battery post and the negative battery cable when the headlight switch was on. In that case the draw was 1.1 amps and both the headlight and taillight relays clicked as soon as the circuit was completed with the multi-meter.

On that car you're supposed to be able to leave the headlamp switch on when the car is shut down because the lights automatically turn off when you pull the key out of the ignition and open the driver's door. It works that way on my '95 Volvo too.

So it is drawing 1.1 amps when the car is shut down, the lights are off but the headlight switch is left in the on position. Why would that be happening? Is the headlight switch likely to be at fault or does it more likely have to do with some other component in that circuit?

I should mention that this is a fairly recent phenomenon. I used to be able to leave the headlamp switch on and the battery wouldn't drain down to zero in a week. Now it only takes a day or two.

Thanks in advance.

DangerBoy

Well, it turns out that turning the headlamp switch off before shutting off the ignition doesn't make any difference. The truck was dead again this morning after sitting for only 2 days.

I did some more troubleshooting and discovered that I've got a 40-50 mA draw on the dome light circuit. With that fuse out the draw goes down to about 10 mA.

I pulled both dome light fixtures and could not find a short in either assembly. Neither could I find a short in the dome light cables.

I did some further reading on some similar threads on this forum and found one where someone had a similar problem on a '99 and fixed it by replacing the stock Toyota radio, which is apparently also on that same circuit. How much power are those things supposed to draw? 30 - 40 mA seems a lot to keep the radio presets memorized in the radio. Anyone else had this problem?

I've got the Dome Light fuse out for the time being. Hopefully, that will stop my battery from being drawn down all the time.

BTW, that other thread I was reading provided a link to a great page on diagnosing parasitic drains. I will paste it here for the benefit of people who come across this thread while searching for help with their parasitic drains.

http://www.aa1car.com/library/battery_runs_down.htm

DangerBoy

Well. the mystery is solved. It just goes to show you that you should never make assumptions and always make sure you do all the simplest checks first and cross those things off the list of possible causes before you start doing the more complicated things.

Because I was not seeing a lot of drain on the battery (~30 - 40 mA) which is not really that extraordinary, I decided to take the battery into the place I bought it from and have it tested. I had assumed because it was only 2.5 years old and was a high end 5 year full replacement warranty battery that it wouldn't be at fault but it turns out I was dead wrong. The test showed it has a dead cell. No parasitic drain after all.

I'm sure glad I spent the extra $$ and bought a battery with a 5 year full replacement warranty on it. It's not going to cost me a cent to have it replaced.

Oh well, onto another project. Many thanks to all of you who went out of their way to welcome me on my first post on yotatech and who tried to help with advice and suggestions. ;-) (Sarcasm)

truckmike26

This is happening to me right now on my '94. A one-year-old battery from Toyota and dead. I watched the ammeter as I pulled every dang fuse with zero change in amps.

truckmike26

Took the battery back. Same thing -- a bad cell. Free replacement on order.