ECU-IG1 Fuse (7.5a) keeps blowing

Greetings all! Seeking advice on diagnosing this. First of all.... my BSMS hasn't worked in years. Keep that in mind as you read. 2014 Tundra 1794 4x4 240K miles.

I'm on the interstate yesterday crusing along when the "Traction Control Not Working" message + CEL comes on. A couple miles later, all of the lights on the dash come on (4LO flashing, 4HI flashing, ABS, BRAKE, Traction Control, and CEL) and the speedometer and cruise control stop working + when I stop the truck is locked in Park unless I force it into gear by pushing button under the cover on shifter.

Stopped at autozone and borrowed their junky scanner. Truck has stored/permanant code p0500 speed sensor.

Stopped at Toyota dealer in Bowling Green, KY. Tyler, service manager, is immediately helpful and gives truck to lead diag tech. A few minutes later, they come tell me that the ECU-IG1 Fuse is blown with a short somewhere and ask me how long I can wait. I tell them I have an hour max. Tech starts digging and he ID's that the left side door mirror might be the culprit. He un-plugs it and the truck no longer blows that fuse. As soon as he plugs it back in, the fuse blows again and dash lights up. Since I needed to get back on the road, they left the mirror unplugged, put my door panel back on, and let me hit the road to get to Louisville for work.

Everything except the un-plugged door mirros works great for about 150 miles. Then I am stopped with the truck running when the dash lights back up and speedo stops. I stop and buy a pack of 7.5 amp fuses before heading back to TN.

1. Replace blown fuse - Lasts for about 5 seconds then pops.
2. Replace blown fuse again - Lasts about 3-4 miles down the road and pops again. (Traction Control Off and CEL still on but no other lights).
3. Drive all the way home to middle TN and replace fuse again when truck is cold today and it blows it shortly after.

I clearly have a short somewhere directly to ground but there are like 999999 systems tied to this 1 fuse.

I have techstream so I hooked it up and I have these *current* codes P0500, U0122, B1421, B1424, and U0129.

Any advise on where to begin if I want to diagnose this myself? Could a bad speed sensor at a wheel or tranny cause all of this, including the blown fuse? I ask that b/c the traction control message came on a few minutes before the dash completely lit up so I'm thinking whatever caused the P0500 code might be the ultimate culprit? Thanks everyone!!

 

So I’m no expert on this stuff, but what I have learned is to look for things most likely fail, like things that move. I’d check the EWDs on this forum and see if you can find out how to test the speed sensor (and which one is bad, I think these truck have more than one)

The other thing that’s odd to me are the two B codes. I believe sensors those are on the dash. They could be completely unrelated and it’s possible the dealer ignored them cause of this. That’s said, Have you checked to see if you had/have a rodent issue?

Diag for this stuff is tough, best of luck.