[pritchet74]

My wife's Sequoia has been having LOTS of problems in the last few months and now it's just getting crazy. In the last year the brake light on the dash went on, although the parking brake wasn't on. I ignored that though. Then shortly after getting the timing belt and water pump replaced the 2 yellow lights in the upper right (trac?) went on. My mechanic ran the codes and it said that a sensor in one of the wheels was bad, but he also noticed that my brake pads were down to about 2%. Since $$$ was tight I just had him replace the pads. That got rid of the yellow lights on the dash.

Somewhere around this time I noticed (my wife never noticed this) that when I put the key in the car and turned it to the 2nd click (just before you would turn the key that final amount to start the car) the car would start. So the car was starting when it wasn't supposed to.

Perhaps a week or 2 after that, my wife went out one morning and the battery was dead. Completely dead. The remote wouldn't even unlock the doors. The lights were in the "on" position, but she always clicks the remote 2x to shutoff the lights. I charged the battery and it was fine for about a week. During this week the temperature display (for the in the car temperature) switched from Farenheight to Celcius. It switched back and forth a couple of times over a few days. It has been fine ever since.

Then we got a knock at our door around 10pm from a neighbor saying that our deadlights were turning on and off. Sure enough they were. I opened the car and turned the light knob to the "off" position. They didn't come on again. About a week later we got in the car and as soon as I started the car the rear window went down all by itself. I put it back up and locked the windows. About 3 other times as soon as I clicked the button to unlock the windows the rear window would go down by itself. It only did it on that day though and hasn't done it since.

Things were fine for about 2 weeks and last Friday my wife's car was dead again. The lights were off though and no other interior lights were left on and nothing else was plugged into the car. She had driven the car on Thursday. I charged the battery again and then on Saturday night we noticed that lights were turning on and off all by themselves again. Then Sunday the alarm would just go off all by itself. It did this 3x during the day. Then I just unplugged the battery.

It's a SR5 base model. No daytime running lights and therefore no DRL relay. I went thru some old threads and fear that I am going to get stuck with having to buy a new computer for about $2000 for the vehicle. I can't afford that, so I am really hoping there is another option.

Any suggestions? Thanks in advance. Jeff

 

[justinjohnson2010]

What did you end up doing with this? My friend has the same battery issue and electrical issues now.

 

[LGL002]

Sometimes when crazy things like this happen it's related to a bad ground connection somewhere on the vehicle. For a while people were reporting that connection on the left side grounding wire that's attached under the hood not far behind the battery. Inside the tail light housings were another location. In reality it could be anywhere there's a grounding wire attached to the body or chassis.

Larry

 

[ITO]

I have very similar issues, with my 2006 Tundra
The truck would try to start itself, and the battery would often be dead. It seemed to work well for a while, then when it rains the trouble starts up again.

After taking it in for repair, the mechanic said he could not find the problem and charged me $900 for trouble shooting. He also recommended I replace the fuse box assembly.

The following things will not work at the same time or will cause the others to not work.
Radio
Blinkers
Windows
AC
Charging

I have replaced the following parts:
Battery
Alternator
ECU
Starting Relay

After spending the whole day I took the 2005 manual and meticulously, checked every fuse, every relay, every ground point (except for two I could not find), and about a dozen connection blocks. After trying to isolate the issue by pulling fuses, I finally got it all working at the same time without actually finding the problem, then when I put it in drive to move the truck, everything stopped working again.

This is my third Tundra and very possibly my last. Once my pride recovers, I may try this again.

Anyone have any suggestions?

 

[Rocketvapor]

I do not know about Toyota wiring, yet, but over the years various ground locations that seemed to be strange actually produced telltale results when a connection failed.
One that was used is the 3 pin door closed switch (the one at the front of the door.
Two different circuits and one or the other could not tell if the door was closed or open. Even various dash lights and partial alarm trigger. Like the flashing headlights.

 

[ITO]

I had a lot of the same problems you listed, this is what I found after working on the truck every evening for the past week tracing out circuits (see below). It looks like moisture somehow got in the fuse box that is in cab under the driver's side dash. I only found it because I needed to test the ACC relay. BTW a new ECU is not $2,000, you can find a used on ebay for $100.

 

[IanTundra27]

I had a lot of the same problems you listed, this is what I found after working on the truck every evening for the past week tracing out circuits (see below). It looks like moisture somehow got in the fuse box that is in cab under the driver's side dash. I only found it because I needed to test the ACC relay. BTW a new ECU is not $2,000, you can find a used on ebay for $100.

Hey man! Did you happen to find where the water was getting in? I just found out i have the same issue. Ordered a new junction box from the dealer. Looking for the leak now.

 

[christophermeeks85]

I’ve read a couple of posts with similar issues of truck starting in the ON position, battery dying, weird electrical problems since I was experiencing the same issues including daytime running lights staying on. This first happened after I went through a touchless carwash with high pressure water. I pulled the cover off my kickpanel and fuse box and found traces of some water plus some rust above the fuse box which lead me to conclude that I had a water on fuse box causing short issues. Based off of some of the posts I read my first place to check was my windshield. So I got soapy water in a spray bottle and sprayed the outside seal on my windshield. I then put compressed air on the inside seam and looked for bubbles. I didn’t see any. But to double check I decided to do a water test. The first thing I tested was the windshield wiper cowling since there are posts I read about grommets that come loose and allow water to drip into cab, though this normally happens on the passenger side above the ac blower. Ran the water only on the cowling and checked near the fuse box and didn’t see any water. I ran water on the top and side seams of the windshield and did see some water. I then pulled the handle on the a pillar and the trim on the driver side to be able to see the seam directly and look for water. I dried the fuse box area up and ran a fan on it for a couple of hours and directed the water only to the side of the windshield seam and low and behold I got water near my fuse box. Upon inspection I can actually see some daylight through the seam and have definitely found the source of my issue. So if you have similar electrical issues that would be the first place I check.

 

[cheapskate]

You, my friend, are a GD genius. You just joined, but rather than starting a new post and asking someone to spoon feed you info that is already out there you found an existing thread and added some insight to it. I have to think you've been on forums before to know this stuff but I could be wrong. And sadly guys like you are more rare than common.
Either way, nice work offering up some input that might help a fellow member down the road.

 

[christophermeeks85]

Thank you. Your previous posts on other threads have helped guide me in the right direction. Since I’m still in the middle of all this, I know the pain and just so relieved to have a solution.