Lost my third computer

I have 2001 tundra 4x4 and I just lost my 3rd computer today. Had an error code 1780 with check engine light on. It seems every time a computer dies water is involved. Could a short in the harness to the tail light or trailer hitch socket cause this? Also when I erase the code then I put it in reverse the engine light comes back on. Not always but sooner or later it does. Also does anyone know which pins on the computer harness I can check to see if I have a short

 

I highly doubt there is anything wrong with your ECM / computer. The P1780 code relates to the transmission range sensor / transmission neutral switch, but yes, a short, or open / poor ground connection to the tail / brake / reverse lights can certainly cause the fault.

Have you checked all the lights to see if there are any malfunctions?

 

It's not an uncommon issue for FGTs for corrosion to be a problem with the transmission wiring harness where it connects to the top of the transmission...I would check that first.

https://www.google.com/search?q=toy...ome..69i57.14992j0j7&sourceid=chrome&ie=UTF-8

 

Thanks for getting back to me. So I have no engine check lite on when I turn on the key and my code reader says it can’t communicate with the computer. This happened to both of the other computers that failed. So now I can’t even get an error code and yes I have checked all my fuses. Can a short in the harness going to the tail light cause the computer to fail? Also I washed my truck just before this happened with most of the water at the back of my truck washing the camper shell

 

If i couldn't communicate, I would be checking the OBD2 connector for the proper voltages. Might be a power issue to that connector.

 

I also want to add that on 3 different occasions while driving in the rain the truck just died. The first took out the computer and the other two I was able to get it started.

 

Yes I have checked that out and it is fine. Remember there is no engine check lite on when I turn the key on which means the computer is bad. So at this time I have a backup computer I’m installing with hopes that what ever killed the last one won’t kill this one. Then I will look for a short. That may sound like I’m doing it ass backward but I need power to the park-neutral switch to check for one

 

Say what? I've never heard this in my life, and I'm fairly sure it's not correct, or I'm really misunderstanding what you're saying.

Sounds like you've got water intrusion into something electrical somewhere. I'm going to guess it's something below dash level, along the firewall, or behind/under the dash. I would pop off the interior fusebox and look at the back side. Have you checked the carpets and firewall during rains?

Other members have reported all kinds of electrical gremlins because water was getting to the combo/bulkhead near the fusebox, and two I've seen in a couple of years had water intrusion into their interior fusebox and found residual traces of green water streaks (dried copper oxide) on the rear of the interior fusebox.

 

3rd brain with no firm answers, I'm calling Carvana.

 

Thanks gentlemen for all your responses and let me say I have checked all of them and no indication of water any where. Just to let you know I’ve been working on this problem for almost 2years now and I even have a factory Toyota service and troubleshooting manual if I could only read it. Lol
So I just installed my backup computer and the truck started up on the first click then scanned for error code and it was clean. I then shifted from park to reverse and bam the damm 1780 popped up so maybe it is the switch. That is where I’m headed next. But I can’t find anything in the manual that covers it.

 

Hesitate to offer considering the ECM's you are going thru but after 2 yrs, what thu hell !

I would consider unplugging both rear lights completely and according to what trailer hitch you have, I would consider unplugging the 1 or 2 connecters just under the rear about foot from bumper.
Have you installed a backup camera and tapped into reverse ?

 

Hey bubba I have read where Toyota had issues with the trailer hitches and I will do that next. And yes I did install a camera but this problem started way before I did that. What doesn’t make sense to me is that if there was a short at the hitch or the backup lights that it would take out the computer. What are your thoughts on that

 

If the ECU is fried it can't light the check engine light or store codes because they're stored in the ECU? That's what I'm thinking anyway.

 

Truck ever been in any accidents? Computer failure is extremely rare. But wiring issues are not unheard of with vehicles this old. You may have a wiring issue getting power to the computer. Swaping the computers out can totally cause it to work just because the wires have wiggled around. I can’t offer a ton of help without having the truck in front of me. But it sounds like hunting down green Crusties or resistance checking key wires Is the step that should be taken. Something as simple as an engine ground can cause the computer to not communicate or illuminate the check light.

 

I'm wondering if you don't have a cowl leak on the passenger side and it's getting into the main harness on the firewall. I'm pretty sure shifty and empty are onto something.

 

Yup. That's essentially where I was headed with my reply (# 9) above.

And for the reference I was thinking of, look no farther than this thread: https://www.tundras.com/threads/02-tundra-electrical-problems.45605/

You'd think Toyota would've done a better job of waterproofing what's essentially a critical part of the wiring nervous system of our trucks.