Toyota Sienna Killing Batteries

Question: Toyota Sienna Killing Batteries

I have a 2000 Toyota Sienna that I purchased 1½ years ago. It has 58,000 miles on it. I absolutely love this vehicle.

4 weeks ago, 5 p.m. on Friday, I had to get a jump start, so I took it right to an auto repair shop and they told me the battery needed to be replaced, so I did.

2 weeks ago, 5 p.m. on Friday, I had a dead battery. I was at work and fortunately we had a battery charger in the shop so I charged the battery. The auto dealer close to my home was open on Saturday so I took my Sienna to them. They checked out the entire vehicle and couldn't find anything wrong.

The vehicle ran good until yesterday, Thursday, 5 p.m., - dead battery. It is at a different auto repair shop now. They are not having any luck finding anything wrong with the electrical, electronic, and every other system there is on this vehicle.

Several things I noticed early yesterday, the A/C ran better when my foot was on the gas. When I got it home last night after jump starting it, the dashboard battery light came on when I stepped on the brake, and when I stepped on the gas it went out.

I drive 3 miles to work, maybe another 7 miles running errands at lunch, and then 3 miles home at the end of the day. Weekends have been spent traveling to dog shows, sometimes 200 miles away until I started have this problem. I rarely have the lights on, close all the doors securely, and after the second dead battery I do not use the security system. Do you have any idea what could be wrong, any suggestions what more we can check.

Thanks for any help you can give me.

Lynda Cowley

Jamestown, California

Answer:

Lynda, so glad you gave such a detailed description of the problem and the events around it. You have no idea how often people leave out little details, unknowingly of course, that can help make a diagnosis.

The big clue here was where you said "...I noticed early yesterday, the A/C ran better when my foot was on the gas." This tells that the idle speed on your vehicle is a little on the low side. So I checked the Technical Service Bulletins (TSB) and found a TSB that applies to your vehicle.

Section: Electrical

Bulletin #: EL013-03

Date: September 26, 2003 (Revised)

Title: Charging Improvement At Idle

Models: 2003 model year Sienna vehicles.

Introduction:

Some customers may complain of a low battery or no start condition after running the engine at idle or low RPM for extended periods of time with several accessories on (for example, front and rear air conditioning) during high temperature conditions. A new alternator has been developed to improve charging performance at idle.

NOTE: This new alternator will not prevent dead batteries or no start conditions on vehicles that are stored for long periods of time or on vehicles that are driven very infrequently.

So what you need to do is go to your Toyota Dealer and have them check and adjust the idle speed. Then have them check for a parasitic draw on the battery. If everything checks out good, or has been repaired, they can then install the modified alternator and that should take care of your problem.

That's all for this week. Feel free to browse the archives for past topics and other resources. And, as always, if you are stuck and need an immediate answer you can always call Vince on the phone.

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