Hazard lights gone crazy

sounds like a short, any vermin?

 

Wiring harness modification where somebody mixed up the hazard circuit with the vehicle speed signal?

There's a pulse-train signal that the combo meter generates, and feeds to other units like the nav headunit. The higher the car speed, the faster the pulses. It would be kind of funny to lead that to the hazards. I'd assume, though, that by itself it would lack the current capacity to drive them. Is there somebody who might want to prank you?

That's almost as good as opening somebody's old CRT monitor and reversing the plug on one of the deflection yokes.

-Chap

 

Reminds me of the time I managed to switch left turn signal light and washer fluid plug-ins...

 

This is the print for the 2010 Model Prius (similar to 2011) if you do not already have one. Should help you isolate where the stray voltage, short...or whatever...is causing your issue.

 

I had problems with my radio when I was doing work and it was a pain in the nice person to find the fuse that blew the labeling of the fuses is very strange. there is a fuse pannel in the engine bay and one under the stearing wheel near the side closes to the door and its a PITA to get to.

 

Am I correct the "relay" you changed was L55 per the print?

Hazard lights acting up | PriusChat

 

Well, two ways:

First, fuse box labeling is always comical. Just like your grandpa's fuse box might have "fridge" scribbled on the label for fuse 8, but really that circuit serves the fridge and six other things that never got scribbled in ... the labels on Toyota fuse box covers are just like that. There's complete information in the wiring diagram though. So a fuse labeled "ABS" is likely to be supplying some ABS stuff and some other stuff, and in the wiring diagram you can find the real details.

Second, you mentioned a symptom that really kind of sounded like something's been crossed with the speed pulse signal. That's a derived signal that's generated based on the actual wheel speed sensor signals. The wheel speed sensors are wired to the ABS/skid ECU.

I stated incorrectly above that the pulsed signal is generated by the combo meter, which would mean it would have to get the wheel speeds from the skid ECU over the network. A quick review of the 2004 New Car Features manual shows that's not how it works (page BE-82); the skid ECU generates the pulse train (which makes sense, since it has the wheel sensor info). The pulse train is an output from the ABS/skid ECU, and an input to the combo meter.

So if the ABS/skid ECU is out of commission, no pulses....

-Chap

 

Well, it seems you have an issue that I'm pretty sure is unique in all the annals of PriusChat.

I'm sure the explanation will be really interesting, but it's just going to take patient poking away at it to find out what's really going on.

I would probably start by trying to confirm or disconfirm my guess that the hazard blinks really do coincide with the speed pulses. That is, check the wiring diagram for the color code of the "vehicle speed signal" wire, and the pinouts of the connectors and junctions where it appears, pick a more easily accessible one, and put something like an LED and resistor on it so you can watch the pulses. Drive around some and see if those pulses really are in time with the hazard blinks.

If they are, then somehow there really is a connection, and more poking around with the help of the wiring diagram might turn it up.

If the blinks turn out not to be in sync, then my guess wasn't right, there's some even stranger coincidence, and it's back to the drawing board to think out what else it might be.

-Chap

 

congrats!

 

John Trap. We're experiencing the exact same problem and wondering if you can provide a picture of the part you replaced. A little confused if it's the actuator or the actuator pump/modual because they both have electrical to them. Just want to make sure we're ordering the right part because we already have $600 tied up into a failed diagnosis from the dealership. Thank you.

 

welcome!
try pm'ing him