Hazards won’t turn off

techinfo.toyota.com

 

I'm suspecting the push-switch is having an issue....owner might've sprayed cleaner or something that got inside of it. Do you have a can of canned air you can attach the little nozzle on and try spraying air all around that switch? Might push whatevers in there far enough to fix it. (Always start with the easy fix!)

 

It sounds like there's some kind of signal interference with your hazard light circuit path. Next step is to figure out where in the car that mostly likely will occur and then buy a used one at a wrecking yard and swap it out. Perhaps @Elektroingenieur will see this and give you a sense of which component or wiring harness location where this could be happening. In the meantime, at least everyone will be extra cautious around you when they see you on the road, so that's a postive.

 

You have the well-known issue documented here. One of the brake ECU's miscellaneous jobs is to generate a pulse signal that tells other things in the car how fast the car is going (by how fast the pulses come). Brake ECU has that job because it has the inputs from the wheel speed sensors.

The brake ECU also has a connection to the hazard circuit, which is only supposed to be an input (so the ECU knows when the hazards are on ... I don't really know why it cares). But those two signals are right next to each other at the ECU's connector, and when they somehow become bridged, you end up with the speed pulse output driving the hazard lights.

It seems like you probably already saw the above-linked post if you removed that HZRI wire. That's what I would do as well. The member LeftyLucy in that thread did so, and didn't get the warnings you've reported. (Also, as far as I know, @LeftyLucy is the person who has made more progress than anyone else yet toward finding out exactly how those two circuits get bridged. I don't think there's a final answer yet though.)

So, because not everybody gets warning lights like you've reported, I have to suspect that something else happened in your case, maybe inadvertent or unnoticed, as you were doing that work. Not to sound like a broken record, to find out why you've got those lights on, just going ahead and reading your trouble codes will be the most help.

If you don't have a scan tool for doing that, you can use the Tc to CG jumper wire method, and count the light blinks. A search should turn up threads with the details.

I'll be interested in what the codes turn out to be.

 

I still hope that somebody, someday, will proceed to disassemble one of the skid ECUs that fails, so that we learn more about just how those two circuits get bridged, and whether it suggests an increased chance of anything else flaking out next.

So far, I'm not aware of anyone besides @LeftyLucy pursuing that.

Mostly just for the use of future readers coming to this thread: as you see, there was a trouble code that pointed pretty much directly at the missed connection that needed to be plugged back in (the computer next to the fuse box is the ECM). That's why we harp on reading the codes; it can save a lot of time and investigation.

 

Can someone please point me in the direction of how to do this? I can't even find a diagram of where the skid control ECU is or even a photo or part number for Gen III

 

The skid ECU is part of the brake master cylinder with booster assembly. Try following the "documented here" link in post #6 above. You will see diagrams of the connector and some photos. Removal of the windshield wipers and cowl gives better access. That's the same as if you were changing your spark plugs, so you can find plenty of threads about that.

 

Thanks. I have changed the plugs a few times. Actually have a new set ready, but car's "only" at 174k.