Hazard lights won’t turn off

Discussion in 'Prius v Main Forum' started by Captain Picard, Jun 2, 2021.

  1. Captain Picard

    Captain Picard Junior Member

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    Hi everyone..

    I know many people have had this issue and now it’s happened to us. Yesterday, our hazard lights turned on by themselves and won’t turn off. The battery drained overnight and we had to get it jumped this morning. We couldn’t get an appointment at the dealer’s service shop until next week. In the meantime, we have a technician at a neighborhood shop taking a look at it. A few questions..

    1) Is this an issue that a non-dealership shop can actually fix?

    2) If the tech can’t fix the issue, we’ll have to take the vehicle back home and the battery would die again. Is there something we can do to prevent the battery from dying while we wait to take it to the dealer? Do we need to disconnect the battery? Is this possible to do without special tools?

    Any help would be greatly appreciated!
     
  2. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Sticking hazard button? Wouldn’t hurt to disconnect neg lead from battery before investigating. That’d stop the battery drain too, for the interim.
     
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  3. ChapmanF

    ChapmanF Senior Member

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    There's a kind of a known issue where the hazards blink in a way that kind of depends on the speed of the car. I think I know how that might be caused. Is that what you've got, or are yours just plain stuck on, flashing at the normal rate?

    What happens if you unplug the hazard switch? Do they stay on still?
     
  4. Tim Jones

    Tim Jones Senior Member

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    # 10 wrench....the battery is in the trunk.. passenger side
     
  5. ChapmanF

    ChapmanF Senior Member

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    I think Tim means a 10mm wrench, which you can use to undo one of the battery clamp posts in the back of the car.

    If that's something you'd do, you might also consider just unplugging the big white single cable in the underhood fuse box. Easier to get to and no wrench involved. Either way, you'd still have to reset your radio stations, clock, auto-up windows, etc. when you reconnect.

    Referring back to #3, got any more details on the exact way the hazards are behaving? There are some related cases here on PriusChat.
     
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  6. Captain Picard

    Captain Picard Junior Member

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    Hi everyone,

    Thanks for your help..


    Basically, the issue has been that the hazards flash at a constant rate no matter the speed we're driving. The only exception to this is sometimes we'd push the hazard button to see if we could turn the flashers off. Usually nothing would happen, but occasionally, the flashers on the dashboard would turn off temporarily or would come back on and blink very quickly before returning to the normal, constant rate.

    The update we have is that we took it to a regular mechanic as that was the first appointment available. They took a look at it but couldn't fix the problem and didn't charge us for their time. But told us that they thought the issue was coming from a module or computer in the dash area. They recommended that we take it to a dealer.

    We got an appointment at a Toyota dealer today. Very disappointing experience. They charged $300 for diagnostic tests and told us that the problem was the combination meter. They quoted me $3000 ($1500 parts, $1500) labor for the fix! Suspecting that something wasn't right, I spoke to Matt from Texas Hybrid Batteries to ask about the cost of a combination meter (thanks Matt!) We both came to the conclusion that the combination meter diagnosis doesn't make much sense, the quote is way overpriced and that I need a second opinion from an electrical specialist.

    The additional disappointment is that after picking up the car from the dealer shop, we now have a new set of problems. The hazard light sound is still clicking, but now the hazards won't come on at all -- and neither will the turn signals, which seems to make the car basically undrivable. Any idea what the dealer could have possibly done to cause this new set of issues? And any idea what we could do on our own to recover the use of at least the hazards?

    Finally: I called up the Toyota service shop at the dealership where I bought the car years ago (they're an hour and a half drive away from where we live now) -- and they gave me a quote over the phone of $1100 for parts and labor if it's indeed the combination meter. But they also agreed to do a new diagnostic test to see if that's really the problem. My concern at this point, though, is how the heck I'm going to be able to get the car to the service shop without hazards and turn signals..
     
  7. Captain Picard

    Captain Picard Junior Member

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    I forgot to add: We haven't tried unplugging the hazard switch. I wonder if the dealership did this today when we took it in, since the hazards are now clicking but not flashing.. Could someone explain to us how to check the status of the hazard switch so we know if it's currently plugged or unplugged?

    Thanks! We figured out how to disconnect the battery to prevent drainage while we troubleshoot this..
     
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  8. Tim Jones

    Tim Jones Senior Member

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    BUMMER!!!!! Guess u could use hand signals.
     
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  9. Tim Jones

    Tim Jones Senior Member

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    Seen this on another site......
    I had a Prius in the dealership today with the hazard lights flashing all the time and the rate at which they flash increases with speed. I also noticed a left rear speed sensor code stored in the abs ecu even though the abs light was not illuminated and I had an active speed sensor signal. The only common connections I could find between the hazard lights/turn signals and vehicle speed is the abs actuator. Using a long hook tool I unplugged the abs actuators electrical connection (without removing the wiper cowl) and the hazards stopped flashing immediately. (Note, doing this will set codes you may not be able to clear) An internal short circuit inside the actuator is the problem with this vehicle. FYI, depending on year and mileage, Toyota has enhanced coverage for the abs actuator on a Prius.
     
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  10. Tim Jones

    Tim Jones Senior Member

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    and anther one...

    Xiao answered 11 months ago

    I had this problem and engineered a fix. The issue seemed to be a short on the harness. My solution involved disconnecting the existing wiring from the flasher relay and jumping a wire from the hazard switch to the relay. The fix is documented in the following thread. Page Not Found | PriusChat crazy.201911/page-2
     
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  11. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Around here, no signals, you’d blend right in. :D
     
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  12. Tim Jones

    Tim Jones Senior Member

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    From another post
    finally got time to work on prius abs actuator was shorting into hazard lights, replaced the acuator with a used one got for 100 bucks two hours of labor and a hard brake bleed and the old car is back up and running thanks for all your advice
     
  13. ChapmanF

    ChapmanF Senior Member

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    Right, the hazards-blinking-faster-with-road-speed issue has been an oddly common one discussed around here before, which is kind of laugh-out-loud in how specific it is; there's really only one way to see that happening. One of the jobs of the brake ECU is to generate a "speed pulse" output (SP1) that goes faster with car speed. The speedometer doesn't use it (just gets the speed over CAN), but other common accessories do, like the NAV for deciding when you're moving too fast to push buttons, or the radio for bumping the volume at higher speeds, and so on.

    There's also a HZRI wire that connects the hazard switch to the brake ECU (I'm not sure why, but I guess so the ECU can know if you've turned the hazards on. In Techstream you can see it as an input.)

    It turns out the SP1 and HZRI wires are right next to each other in the connector to the brake ECU under the hood, as discussed more in this thread.

    [​IMG]

    If that problem ever happened to me, I think I would do a quick look for corrosion or tin whiskers right near those two pins, before I would jump to any more drastic conclusions about failure of the $$$$ actuator. (I might also think about just sticking a diode in HZRI. If it's just meant as an input to the ECU, then it doesn't need to be able to trigger the hazards from there.)

    That might none of it be on point for the OP though, since this is a different situation where the hazards are stuck on at a fixed blink rate. So they're not being bridged to SP1 in this case. There could still be something just bridging that circuit to ground though. Worth a look.

    Well,if you currently hear clicking but don't see light, it's more likely they disconnected something downstream of the flasher (or pulled a fuse maybe, though I haven't checked the diagram just now for what fuse that would be). If the problem were the switch and they unplugged it, the clicking would stop.

    I'm not familiar with exactly where the switch is in a v or just how the v's panels pop out, but it's usually pretty simple.
     
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  14. Captain Picard

    Captain Picard Junior Member

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    Hey everybody! Thanks again for your help..

    Here's an update:

    Took the car to the Toyota Dealership where we originally bought the vehicle. After two days, they gave us what seems to be the common diagnosis: a problem in the ABS module. They quoted the cost of the repair as $1285+ tax, for a total of $1400 (sigh). This is, however, less than half of what the first Toyota Dealership we went to wanted to charge. The other shop provided a fake/false diagnosis (the combination meter) and estimated the cost as $3000 - more than triple of what it should be. There was absolutely no problem with the combo meter -- a short would have taken the whole screen out in all likelihood and the only issue was that the hazards weren't flashing (and the first dealership disconnected something to make the directionals stop working too -- perhaps in a futile effort to make us believe the combo meter needed replacing?)

    Anyways. We are hoping for a quick repair and hope to have the car back this weekend..
     
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  15. Captain Picard

    Captain Picard Junior Member

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    Thanks for your help, Tim! Just circling back to say that the dealer shop isolated the problem as being in the ABS module.
     
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