Jerry From LA SuperDork
Jan. 11, 2017 5:27 p.m.

Hello Everybody,

My wife's 2010 Sienna has a short circuit that killed a battery. I'm looking at over 40 different circuits spread between three fuse boxes. I'm gonna start by disconnecting the negative terminal on the battery and pulling fuses. My first question:

  1. Is there a known failure place where I can look and maybe cut my workload down? The only thing I found was a recall for faulty seat heaters but I don't think her Sienna is equipped with them.

  2. The little fuse puller thingy was missing out of the fuse box. Is there a substitute I may have in my toolbox that won't nick/ crack/ destroy the fuse? They're the micro-blade type. I can't even get in there with my smallest needle-nose pliers.

Thanks in advance,

Jerry

Dr. Hess MegaDork
Jan. 11, 2017 5:43 p.m.

My friend is going through this same thing with his 98 Camry. I suspect the alarm/remote entry module, but it is just a hunch at this point.

Put an amp meter in the negative battery lead to ground, then start pulling fuses and watch the current draw for a change. Keep in mind that when you first hook it up, the draw will be greater, then reduce as the ECU boots up. So wait for it to stabilize before you start pulling fuses. Then pull the relays one at a time too. Some of them have power all the time.

Streetwiseguy PowerDork
Jan. 11, 2017 5:52 p.m.

First, make sure the glovebox is closed properly. Take a peek with through the windows in the dark, look for a glow from something that shouldn't glow. Then unplug anything not OE Toyota.

As in the advice above, turn everything off, ammeter in series from the negative cable to the post. If you need to have a door open, latch the striker with the door open so it doesn't keep the body module alive.

Wait 30 minutes or so, and the draw should be down below 40mA. If its not, pull fuses until it drops, then science out what that circuit feeds. If the draw after its asleep is more than 200mA, something major (like an alternator) is on or shorted.

I hate parasitic draw diagnosis.

Jerry From LA SuperDork
Jan. 11, 2017 6:06 p.m.

My VOM will do 10 amps. Hope that's enough...I usually put the probes between the negative batt terminal and the disconnected negative cable. Since I didn't have a fuse puller, I started with some of the low-hanging fruit like the ECU relay, etc. I'd rather have my wisdom teeth pulled than do a power draw diagnosis, especially when even the interior lights are connected to some type of microprocessor. This thing has more circuits than my house.

Dr. Hess MegaDork
Jan. 11, 2017 7:21 p.m.

10 amps is more than enough. The draw is probably less than 1 amp.

Jerry From LA SuperDork
Jan. 11, 2017 8:16 p.m.

Probably. it could be quite a bit if an alternator diode has shorted. First thing, I'll be pulling that wire and comparing.

Jerry From LA SuperDork
Jan. 11, 2017 9:27 p.m.

Right now, immediately after disconnecting the battery, the draw is 76 milliamps.

Jerry From LA SuperDork
Jan. 11, 2017 11:05 p.m.

An hour later, same amperage.

dculberson PowerDork
Jan. 11, 2017 11:50 p.m.

That's not out of the realm of reason. Are you sure the battery didn't just fail from age?

Jerry From LA SuperDork
Jan. 12, 2017 12:13 a.m.

In reply to dculberson: The batt was exactly two years old which is why I'm looking for causes. Yeah, I was a little shocked too but I had the VOM set to 10 amps and it read .076 amp. I still have the negative cable removed so tomorrow I'm going to pull the alternator wire and re-test. It's entirely possible the batt itself shorted out. They don't last long here in CA with the underhood heat in the summer. Much more than four years is some kind of miracle. However, the thing should last more than two years.

You'll need to log in to post.

Also on Grassroots Motorsports

MX-5 Cup Racing: Live on Your Screen This Friday and Saturday

2 days ago in News

Catch all the action of the Global MX-5 Cup race at Road America live this weekend.

How to Run Compressed Air at Home

2 days ago in Articles

A guide for installing an air compressor and air tools in your home garage.

2017 Volkswagen Golf SportWagen TSI 4Motion

2 days ago in New Car Reviews

Say hello to the Volkswagen Golf SportWagen TSI S with 4Motion. It comes with a turbocharged 1.8-liter engine that is ...

You Need This: $1600 Street Racer Ford Festiva

2 days ago in News

It already has a GRM sticker and everything.

Get Your Subscription Combo Deals!

2 days ago in News

Get both our magazines for the price of one!

Your Projects: smokindav’s VW GTI Project

2 days ago in News

Love a good MK5 GTI? You might enjoy this build thread.

Wing It: Simple Talk on the Complex Subject of Aerodynamics

3 days ago in Articles

Whether sleek, boxy or somewhere in between, all cars interact with the air while racing down the track.

2018 Acura TLX V6 A-Spec

3 days ago in New Car Reviews

Acura is introducing something new for the 2018 model year: the Acura TLX V6 A-Spec. It's the highest trim level ...

You Need This: 1989 Suzuki Swift GTi

3 days ago in News

For sale: one of Suzuki's under-appreciated hot hatches.

Buyer's Guide: Chevy Cobalt SS

3 days ago in Articles

All the information you'll need on GM’s entry in the sport compact wars.

Wednesday Night GRM Live: Are You Using the Right Chemicals for the Job?

4 days ago in News

What do all these cans even do!?!?

Project SVT Focus Gets Caught Up on Maintenance

4 days ago in Project Cars

Once again, some off-road action sent our project focus under the knife.

OUR SPONSORS

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More
tWrvJ0JkFpNv9L0xMW82Y9VYnYl4LuBR