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Discussion Starter #1
Has anyone recently, or could anyone now, check how many mA their car draws when off with all doors closed? I've been having trouble with the battery draining if the car is not driven for a few days. When I hook up the mulitmeter in series with the battery I get and initial mA read of about 350ish, which drops down to a steady 214 mA after about a minute. Is this consistent with other Siennas out there? Mine is an 2004 LE.

I've read a generic recommendation that anything above 50mA is excessive, though wanted to double check this. As a side note, nearly all of the draw is through the ECU-B circuit.

Thanks.
 

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I'm not sure if there is anything different between our model years that would affect the measurements, but here is what I found when looking at the exact same issue (on my 2010 LE)

"Resting" Amps (amps drawn after all doors have been closed for a few minutes): 10mA but would change a bit and occasionally peak to 940mA briefly. You are getting a steady 214mA draw, which doesn't sound right to me.

Other interesting data I found:

key light only, all other interior bulbs removed: 350mA
All interior lights on: 3A
1 front door open: 890mA
2 front doors open: 1.27A
Amp draw while locking doors via remote: 5.37A
Amp draw while unlocking doors via remote: 9.45A
1 sliding door opening: mostly 7A, but peaks to 16A
1 sliding door closing: mostly 6A, but peaks to 11A

Also note that if any of the rear overhead lights are manually set to the "ON" position, they will NEVER time-out or turn off until you push that light again... I've had the kids leave one of the rear overhead lights on overnight and that is enough to drain the battery enough that the van won't start. (The combination of no light timeout plus a weak reserve rating on the stock battery sucks.) It's been on my todo list now to figure out a way to add a timeout to the rear cabin overhead lights, but haven't had time...
 

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Power draw drops down in steps on cars. The provision for 'key off operation of power windows', etc., means that the body ECU is still awake for at least 10 minutes after shut down. I found from a little research that a steady state draw of 75 ma is considered max after everything goes to sleep. But about 5 hours after shutdown, the Evap monitors run, so that will rise substantially during that test, and then everything should go back to sleep.

One thing to be aware of when attempting a draw test. Your milliameter needs to be in series with the battery, but you cannot break the connection to the ECU to insert it there without glitching the test. Simply lifting the negative battery terminal, no matter how fast you do it, will depower the ECU for a few seconds, and that will change everything! It's tricky to do, but you must maintain connection of the meter to the clamp and the terminal as you lift the terminal, so that there is always a current flow.
 

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Discussion Starter #4
I'm not sure if there is anything different between our model years that would affect the measurements, but here is what I found when looking at the exact same issue (on my 2010 LE)

"Resting" Amps (amps drawn after all doors have been closed for a few minutes): 10mA but would change a bit and occasionally peak to 940mA briefly. You are getting a steady 214mA draw, which doesn't sound right to me.

Other interesting data I found:

key light only, all other interior bulbs removed: 350mA
All interior lights on: 3A
1 front door open: 890mA
2 front doors open: 1.27A
Amp draw while locking doors via remote: 5.37A
Amp draw while unlocking doors via remote: 9.45A
1 sliding door opening: mostly 7A, but peaks to 16A
1 sliding door closing: mostly 6A, but peaks to 11A

Also note that if any of the rear overhead lights are manually set to the "ON" position, they will NEVER time-out or turn off until you push that light again... I've had the kids leave one of the rear overhead lights on overnight and that is enough to drain the battery enough that the van won't start. (The combination of no light timeout plus a weak reserve rating on the stock battery sucks.) It's been on my todo list now to figure out a way to add a timeout to the rear cabin overhead lights, but haven't had time...
Thanks for all the information. The fact that your Sienna only pulls around 10mA confirms my suspicion that I have a parasitic drain somewhere related to the ECU-B. Now for the fun part . . .
 

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Discussion Starter #5
Power draw drops down in steps on cars. The provision for 'key off operation of power windows', etc., means that the body ECU is still awake for at least 10 minutes after shut down. I found from a little research that a steady state draw of 75 ma is considered max after everything goes to sleep. But about 5 hours after shutdown, the Evap monitors run, so that will rise substantially during that test, and then everything should go back to sleep.

One thing to be aware of when attempting a draw test. Your milliameter needs to be in series with the battery, but you cannot break the connection to the ECU to insert it there without glitching the test. Simply lifting the negative battery terminal, no matter how fast you do it, will depower the ECU for a few seconds, and that will change everything! It's tricky to do, but you must maintain connection of the meter to the clamp and the terminal as you lift the terminal, so that there is always a current flow.
I noticed that when I hook up the meter after disconnecting the negative cable there is a surge (around 350mA) that then drops down after a minute or two to what I am assuming is the baseline draw (which, in my case, is just over 200 mA and apparently indicates a parasitic draw). This is the case even after the car has sat for many hours without having been driven.

Thanks for your thoughts.
 

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Discussion Starter #6
Update in case anyone is interested or having a similar problem: based off of some of the above recommendations I exercised a bit more patience and kept the meter hooked up in series for a bit longer. Draw started off at about 350mA, after about 30 seconds drops to just above 200mA, and after another minute or two it drops down to just above 10mA. So, my problem is thankfully not a parasitic draw but was a bad battery, which Costco swapped out. Lucky I caught it at 35 months. The warranty expired at 36 months. Typically one catches these things at 37 months. . .

Thanks again to those who shared their knowledge.
 

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So, my problem is thankfully not a parasitic draw but was a bad battery, which Costco swapped out.
This is *exactly* what happened to me!!!

Every time my 2005 Sienna sat around for a few days, it wouldn't start, and I'd need to jump it. I used a multimeter to test the battery (both off and running). That was my very basic mistake. This video here is what I watched: https://youtu.be/COJr7OB23Hw

So, thinking that the battery was totally fine, I then went on looking for a parasitic drain. The van would begin at about 1000 mA (1 amp) and then quickly drop and stay at 200-250 mA. I thought, "Oh, this is bad, because the recommendation is no more than 50 mA." So I discovered that after pulling the ECU-B fuse, it would drop to zero. Apparently, the ECU-B fuse is what is pulled when Toyotas are sitting in storage for long periods (like, before they go to the lot, etc). I drove the van again, and then it sat in the driveway for about 24 hours.

Then... IT WOULDN'T START AGAIN.

So I was scratching my head, thinking it could be starter solenoid contacts. My thinking was that the battery tried to send the voltage to the solenoid on the starter, but the contacts were too worn or dirty to send/receive enough voltage. So the battery needed to be at 100% in order to give enough power. If the battery was at anything less than that, then it's not enough to turn over the engine.

But I was wayyyyyyyyyy overthinking things. My dad insisted that I just take the battery out of the van and get them to do a load test on it (it's free). I insisted that the battery is fine since I checked it with a multimeter.

But in order to properly test batteries, they *need* to be tested with a LOAD TESTER. A load tester puts a load on the battery (separate from the car... you're disconnecting it from your car), and tests it that way. Otherwise, stuff like the alternator and whatnot is going to interfere with multimeter test, making up for what the battery is not able to do.

Well... the test at Canadian Tire showed that the CCA (cold cranks) on the battery were almost HALF what they were supposed to be. Guess what? The battery was also from 2008 (9 year old battery, lol). I replaced the battery, and popped back in that ECU-B fuse, and everything works as good as new. No more starting issues. And I still don't drive the van much (I'm at home with kids, so I sometimes I only use it once or twice a week).
 

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Simply lifting the negative battery terminal, no matter how fast you do it, will depower the ECU for a few seconds, and that will change everything! It's tricky to do, but you must maintain connection of the meter to the clamp and the terminal as you lift the terminal, so that there is always a current flow.
This is why some techs prefer the voltage drop method. When current runs across a fuse, there is always a little voltage drop that can be measured. In turn there are reference charts to show how much amp usage per fuse type. So you don't have to disconnect the battery momentarily and thus reboot all the various computers.

Here's the minifuse chart
http://cdn2.hubspot.net/hub/232160/...ge_Drop_Chart_-_Mini_Fuse.pdf?t=1492759023710
 

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I understand the concept of the voltage drop method, but wonder how consistent the results are fuse manufacture to fuse manufacture. There's a lot of tolerance in any manufacturing process, there are fast and slow responding fuses, the fuse wire can be one of several metals or alloys, the plastic surrounding the wire can shunt or impede thermal flow which in turn will change the drop, etc. But yes, this is a good test for a specific, targeted fuse - if you have accurate drop data from the manufacturer.

Like any test, you need to know how to perform it, and why. It's not that hard to lift a terminal without screwing up a current test. And it's a great place to start, as it evaluates the entire system.
 

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That maybe true about the manufacturer differences, but anyhow it seemed to work great when I tested this method a while back. I also forgot to mention the other benefit- you don't have to pull fuses either. It's a completely passive method. I could see how someone could be led astray by pulling various fuses tied to various computers and then seeing the amp draw during reboots.


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This is a very informative thread. I have a 2006 XLE that is killing my battery. I just went and got a brand new battery, plugged it in with the multimeter in-series and watched the current draw.

Right at hook up it was drawing over 10A for a few seconds

Then it quickly dropped to under an amp. Having read the thread i knew it may take some time to settle down completely so i went and did some other things. I came back 11 minutes later (i had a stopwatch running on my phone) and it was at 325mA. Not great, but maybe it wasn't settled yet, so i went back to my other task.

I came back at around 40 minutes or so (lost track of stopwatch) and it was still around 300mA. Not good.

I started pulling fuses and nothing dropped it. After i pulled the ECU-B fuse nothing happened (still 300mA) but when i plugged it back in draw went up a bit as the computer re-booted or something. Maybe it was 500mA to 1A, i don't remember exactly. I pulled every single fuse in the box under the hood and nothing eliminated that 300mA draw.

Then i went to the fuse panel by the parking brake pedal. I had the door open so the 'resting' draw was higher now (1.3A i think, i wasn't taking many notes). I pulled every single fuse there looking for something to change the draw and nothing did. Now that i'm writing this and thinking about the process, there may be better ways to perform the experiment. It would be nice to check the under-dash fuses with the doors all closed but i don't know how i could access them without the drivers door open.

Anyway, i don't know what the heck is causing the drain! There is nothing plugged into any of the 12v sockets. I can't hook up this new battery to a car that is pulling .3A, it'll wreck the battery in no time.
 

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Of course! Ugh that's so obvious once you say it. Thanks for having a brain, lol.

I'm not confident that will allow me to find the problem but it's worth a try.

What else can I check if I still can't find a fuse that eliminates the draw? Maybe I'll put the new battery in and go for a drive to allow all the computers to cycle and then shut it down and let it rest and see if my current draw goes away. Maybe it's not in a normal State because it hasn't been driven or used since the battery was replaced.
 

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If it isn't something fused, your that means the issue is upstream of the fuse boxes or maybe something relayed (headlights, horn, etc.) instead. It's also possible that it's something like a main wiring harness short. This happens often in the winter for those in rural areas. Mice crawl in and start chewing on the insulation.
 

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What else can I check if I still can't find a fuse that eliminates the draw? Maybe I'll put the new battery in and go for a drive to allow all the computers to cycle and then shut it down and let it rest and see if my current draw goes away. Maybe it's not in a normal State because it hasn't been driven or used since the battery was replaced.
Do that. Drive it at least a half an hour on the highway with the headlights off and let the alternator fully charge that new battery.

Any aftermarket accessories installed? Trailer wiring, audio, etc.
 

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Ok, i taped the door switch down and watched for current drop while pulling fuses under the dash. None had any effect.

I drove the car until fully warmed up, then shut down and checked the draw. Exact same results as previously, even more than 30 minutes later, still 300ma.

I pulled out the air box and intake snorkels, battery, etc. and removed the plastic engine cover. Looked all over for signs of chewed wires. I got underneath and looked up for same. I found some rodent poops and seed husks but not a lot, and no nesting or collected materials. Didn't see any chewed wires at all (or anything else chewed up).

I'm not sure what to do next. Fortunately I don't have much need for the car right now!

I do have a trailer light plug, it's a vehicle specific model that plugs in-line at the tail light connector. I unplugged it and did not see any change in the phantom draw. I don't think I have any other aftermarket wiring.

I do have a DVD player but I think it's a factory option and in any case must be downstream of a fuse, right?

I'm afraid that if I take it to a mechanic, they'll put in a bunch of hours trying to track it down.
 

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I'm afraid that if I take it to a mechanic, they'll put in a bunch of hours trying to track it down.
They DEFINITELY will! Electrical shorts are the worst, most expensive diagnostics because, after your fuse-pulling exercise, there's really no other options.

"I found some rodent poops and seed husks but not a lot, and no nesting or collected materials. Didn't see any chewed wires at all (or anything else chewed up)."

When you find the chewed wire(s) and/or the nesting/collected materials, you will probably find your short too. I assume you pulled the horn and headlight relays too? Way back in the day when everything was high-powered and analog and there were only 10-20 circuits in a car, you used to be able to buy clip-on inductive test lights which would help with the diagnostics. Now, I'm not sure those exist anymore.
 

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When you find the chewed wire(s) and/or the nesting/collected materials, you will probably find your short too.
Yeah, i believe that. That's why i was really trying to find any kind of nest or anything. I'm hopeful that it wasn't parked long enough for that to happen, and that the critters started checking the van out but had not yet moved in!

Maybe i'll just put a battery disconnect on it, lol. ugh

I did not try pulling any relays. Maybe i'll give that a shot. I guess i was figuring that they were all downstream of a fuse and/or that they'd be pulling a lot of power if they were pulling any, but i suppose that might not be the case.

thanks for the responses
 
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