Hello, new member here. This is a little unconventional but my vehicle is actually a 2009 Lexus GX470, which I’m told is similar to a Runner. Unfortunately it was jumped in reverse and I am having some issues. I tried a Lexus forum but no one responded to my question. Hoping someone can help, because it may be pretty expensive through a mechanic. I posted my question as a reply to a thread where someone is having a similar problem here:
Crossed Jumper Cables--no brakes, all maintenance lights on and beeping

I couldn’t start a new thread bc I haven’t met the 15 post requirement yet. Up to 9!

If anyone can help and reply to my question, would be really appreciated.

Welcome to the forum. Sorry to hear about your GX470. You may have blown one or more fuses and/or burned out some electrical component such as the ABS controller or ECU. I would start by checking for blown fuses and inspecting the fuse box itself for damage. Also, sniff around the engine compartment for a burned plasticky-smell and investigate those areas to localize the source.

Thanks so much for your reply. It’s the ABS MTR fuse that is blown, and will blow right away when replaced. A bunch of dash lights are on with a lot of beeping, and the brakes are soft. The incident happened several months ago, I’m not sure if the sniff test would work??? I was thinking I would disconnect the Skid Control ECU (first component after the fuse) and then pop a new fuse in. If the fuse still blows, I would know if the wire that goes from the fuse to the ECU is shorted to ground. If it doesn’t blow, I guess I would assume it’s the Skid Control ECU?? I am trying to find the location of the ECU on this model through Google searches, but so far no luck.

Sounds like you're further along in determining the problem. The smell doesn't really ever go completely away. But if that much time has passed, most of it will have dissipated. Check out this thread. Start at post #10:

Crossed Jumper Cables--no brakes, all maintenance lights on and beeping

and this one:

Check engine light, vsc light, traction light all on after a short circuit

You might also try looking at the 2006 4Runner manual here:

Service Manual Download Links

Thanks for the links! The first link you mention is actually how I got started on this forum because it’s my exact same problem. So I had originally posted my question there but I wasn’t sure if anyone would respond since it wasn’t a new thread. The manual is super helpful. I spent several hrs today trying to Google the location of the Skid Control ECU to no avail. The manual says it’s part of the Hydraulic Brake Booster assembly. I’m not sure how far the similarity between the 4Runner and GX470 goes, but I did see one other reference when I was researching the GX that it is mounted to the Master Cylinder, which is also part of the Hydraulic Brake Booster. So hopefully that’s where it actually is on my model! Now I just need to figure out how to access it. From the drawing (attached) I can’t tell if I get to it from under the hood or from behind the dash, and I don’t have access to the vehicle right at the moment. So I guess I’ll have to wait and see. At least I have a starting point now. Any other insights, let me know. Thanks!

Attached Images

 

In case anyone else ends up having the same problem, here is what I have discovered. The Skid Control ECU is part of the Master Cylinder Solenoid, which is why you can’t find the Skid Control ECU as a separate part online. After I finally located the ECU, I disconnected it and was able to test it. The power pin and the ground pin are at the same potential, so pretty sure the thing is fried. I used a 2006 4Runner manual to figure out which pins are which. I plan to replace the entire Master Cylinder, because I think you have to take the whole thing out anyway and partially disassemble it to replace the Master Cylinder Solenoid. They sell the whole unit used on eBay for $400-$600. So hopefully that works!