Another ABS, VCS, yellow brake light warning question

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by sharpdad, Aug 13, 2022.

  1. sharpdad

    sharpdad Junior Member

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    Hi all,

    2006 Prius. 145k miles. Replaced hybrid battery around 105k miles. Replaced 12v battery a few years ago.

    My daughter drove it to work at 7 am this morning in Pennsylvania on the first cold morning (55-60) in a long time. Yellow emergency brake light (!), ABS and VCS lights all came on for about 30 seconds as she backed out of the driveway and went to work. She has about a 10 minute drive and said as she parked the car and reversed to fit better into her parking spot they came back on again. (This was all told after she returned home from work). She ran an errand after work 8 hours later (and 80+ degrees out) and another 15 minutes worth of driving and no lights.

    After she was home, I tested the new-ish battery (3 years?) and it was 12.7v in the trunk with the car off, 12.1v in accessory mode (in the trunk and in the maintenance screen) and 14.2v when the car was turned on.

    Front brakes were redone a year or two ago but a local mechanic and dealer did the rear rotors(?) about two months ago. The coolant control value was also replaced - the one that controls the heater vs AC system not the inverter one.

    I just took it for a 15 minute drive and it seems fine. Brakes are good, slamming on them stops the car quick, no softness, etc. No lights at all. The hybrid battery was low when I started (2 bars) but gained a few as I drove. Trying reverse a couple of times (out of the driveway, in a parking lot, etc.) also showed no lights.

    I've read a bunch of the threads and the paperclip technique to get the brake codes but thinking of just taking it to the dealer for them to check it out. I don't want to mess around with a car my 17 year old drives.

    With the lights off will the dealer be able to get any codes? Or do I need to wait for the lights to come back on again? We are reluctant to have her drive it at this point and she's back to school in 2 weeks in any case.

    Any thoughts/suggestions/opinions?

    Thank you very much!
     
  2. JC91006

    JC91006 Senior Member

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    With the car in READY mode, go out and open the engine compartment. Do you hear a rattling noise that comes on for 10 seconds and stops? If your brake actuator is leaking pressure, it would constantly cycle making that rattling noise often. If it's not leaking, you shouldn't hear this noise (maybe one time) but no more. I would say stand there for a few minutes and see if that rattling noise comes and goes during that time.
     
  3. sharpdad

    sharpdad Junior Member

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    Thank you. The car has been sitting for an hour or so and when we turned it on there was definitely a 10 second rattling noise that stopped. The engine kicked on at the same time and was on for 20-30 seconds then stopped. After that there was a whine in the engine compartment that did not stop. Here's a video link to that noise:

    Dropbox - IMG_0274.MOV - Simplify your life

    Whine was constant for several minutes or more.

    We turned the car completely off and back on again a couple of times and there was no rattling noise again.

    A slowly dying brake actuator maybe? If I went to Autozone/Advanced Auto Parts/etc. would I get a code that would help diagnose the issue?

    Thank you again.

    Edit: the other thing I would add is when I was driving it and slammed on the brakes I did manage to make the tires squeaked like they were skidding(?). It didn't feel like the ABS thump-thump-thump braking if that makes sense.
     
  4. bisco

    bisco cookie crumbler

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    they will read the codes for free, but they can't always read all the codes due to the number of prius ecu's.
    it's worth a try before dropping $150. or whatever at a dealer or hybrid shoppe
     
  5. SuzyGS

    SuzyGS Member

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    I read your post with a lot of interest because my daughter's 2008 Prius is displaying the same warning lights: ABS, VSC (also air pressure light and circle warning light). And her car is similar to your daughter's car: 159K miles, new hybrid battery around 100K miles, brakes recently worked on, initial rattle that stops. Will you report back what you find out? I talked to a shop that works on hybrids and they guessed my daughter's car was going to need a new actuator, which they warned could be $3-$4K! I hope that's not the case with your daughter's car and I would really appreciate it if you could update us once you find out more. I have a Toyota dealer appointment set up for Wed and based on a previous incident, I know they are either crooks or incompetent so I'm really dreading it.
     
  6. ChapmanF

    ChapmanF Senior Member

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    Best way to get good prognostications about what your car's issues will turn out to be is to post the trouble codes from your car for us to chew on. They might not be the same as sharpdad's; there are a couple hundred possibilities.

    Your car can blink the codes out for you on the dash lights if you just touch two terminals (Tc and CG) with a short wire, so if you wanted to get a head start on identifying the problem without waiting for the crooked or incompetent dealer to do it on Wednesday, you could search up some of the existing threads here on that, and post the codes you get.
     
  7. SuzyGS

    SuzyGS Member

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    I can't believe someone replied so quickly! Wow. I do want to state I am not trying to hijack this thread, but found it interesting because the cars were similar and it would be interesting to see how this plays out. I will look up the method you described and see if that's something I can do. I did just notice the brake fluid is WAY overfilled. Grrr.
     
  8. sharpdad

    sharpdad Junior Member

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    Our dealer appointment is Thursday and will post the results. One question not answered: if the lights are off with the brake computer still have failure codes to report?

    my daughter has admitted she may have driven once or twice with the parking brake on for a while
     
  9. ChapmanF

    ChapmanF Senior Member

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    I don't think it will blink any codes if the lights are currently off, but it may have historical ones recorded that a scan tool can retrieve.
     
  10. sharpdad

    sharpdad Junior Member

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    The only code my dealer could read off the brake computer was a historical faulty brake switch sensor. "There's no guarantee it will fix the problem" but their recommendation was to try a new switch. $250.
     
  11. bisco

    bisco cookie crumbler

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    wow, thats pretty poor diagnostics. i would ignore it unless the lights come back on
     
  12. sharpdad

    sharpdad Junior Member

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    Heh, I think it's a great diagnostic! It could be your-brake-actuator-is-dead code(s) and we want $3k+ to replace it and I need to junk the car. And buying a new/used car right now is painful. We have been looking around the past week and amazingly little inventory everywhere.

    This is a car my 17-year old drives mostly and the last thing I want is her to get stranded somewhere because the brake sensor dies fully and then the car won't start because it doesn't sense the brake is being pressed. Or her brake lights don't work during a drive.
     
    #12 sharpdad, Aug 18, 2022
    Last edited: Aug 18, 2022
  13. bisco

    bisco cookie crumbler

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    if the brake switch is faulty, the car won't start
     
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