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ABS problems: Dash lights? OK to drive around town?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by CLCL, May 8, 2024.

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  1. CLCL

    CLCL New Member

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    Location:
    San Jose, CA
    Vehicle:
    2008 Prius
    Model:
    Two
    I wanted to take my 2008 Prius on a long road trip, so I took it to the mechanic for a thorough inspection, and they scanned the computer. This wasn't my usual mechanic and I have a fishy feeling about him. There were NO lights or maintenance warnings on the dashboard. It has over 200,000 miles.

    The mechanic told me that the computer showed two problems with the ABS:
    -The wheel speed sensors need to be replaced
    -The ABS pump was showing errors (They tried a cheap fix for this and told me to drive it until my next oil change)

    However, from my understanding, if there are brake issues, dashboard lights will come on. I took my car to the Toyota dealer awhile ago for a different brake question, and he assured me that if there aren't lights on, there isn't anything to worry about. The mechanic also told me the brakes would feel different if the ABS pump was failing, and I did not notice anything.

    Are either or both of these problems okay to choose to live with? Another consideration is that I live in sunny and dry California, where braking conditions are good. I've driven older cars and know how to pump the brakes. If I could choose to live with it (one or both issues) and only use it as an in-town car, I might do that.

    Tl;dr: Two main questions:
    1) If there are ABS problems, shouldn't a dashboard light warn me of that?
    2) Is it okay to drive a car in warm and dry conditions if ABS doesn't work?
     
    #1 CLCL, May 8, 2024
    Last edited: May 8, 2024
  2. Tombukt2

    Tombukt2 Senior Member

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    I've driven your exact vehicle for 6 months with ABS lights on breaks not working as expected but once you understand how they work it's not a big issue and so on so there's always that generally speaking of Prius can not not stop at least in these years of manufacture We have not been able to get the car to not be able to break and it's not sporadically either it's just like an old truck without a brake booster and a four drum brakes You don't remember any of that well there you go so there's always that sunny of California or not I'm in Sunny North Carolina and I'm not kidding I buy these cars all the time with the brake actuators needing replacement and I drive them for months while I search out a worthy used candidate to get a break actuator from and even then that fail so sometimes I'm driving the car for 9 months with the lights on on the dash and it breaking like an old timey truck no problem you expect it and that's that works fine still getting 47 mi to the gallon all of that but I'm sure others will be here along to tell you that you could endanger half the plan it on the road and what have you but these are my experiences and we do this very regularly enjoy.
     
    #2 Tombukt2, May 9, 2024
  3. ChapmanF

    ChapmanF Senior Member

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    Vehicle:
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    Model:
    IV
    Taking the second post first, Prius brakes are a complicated system that has more than one way of failing. The failure modes Tom describes, where you can just press extra hard and stop the car, like an old one without power brakes, are the more common ones, thankfully.

    Other failure modes where the brakes will not stop the car (floored-pedal-no-stoppie) are rare (again, thankfully) but possible. There are reports here on PriusChat and reports filed with NHTSA. What I suspect about those failures is that they involve unbled gas bubbles in the system, combined with another event that triggers fail-safe mode. Normal operation is pretty good at masking the effect of bubbles in the system, but the fail-safe mode isn't (and so it does not really fail "safe" in those circumstances).

    So I do advise being less cavalier about brake issues than Tom is.

    But getting back to the first post, if you haven't got any brake misbehaviors that bother you, and you haven't got any brake warning lights, I agree that your fishy mechanic sounds fishy and your dealer sounds right, and you should go drive and enjoy your car.
     
    #3 ChapmanF, May 9, 2024
    CLCL likes this.
  4. CLCL

    CLCL New Member

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    Location:
    San Jose, CA
    Vehicle:
    2008 Prius
    Model:
    Two
    Update:
    The ABS pump was fixed by bleeding the line and getting rid of bubbles (the try for a cheap fix I mentioned).
    The ABS wheel speed sensors were actually not bad -- it turned out that the 12V battery was (very slightly) low and that was causing the error code.
    The mechanic was not lying to me, but he's not a good mechanic either -- he did mention a new 12V battery might help, but he should have insisted that we try a new 12V battery before saying the wheel speed sensors needed to be replaced (about $1k). I miss my old mechanic.

    Also, thank you both very much! You really lowered my blood pressure when going to get my car re-checked today.
    I think both of you and the dealer were right, that if there was actually a brakes issue, that it would show on the dashboard.

    Tl;dr: Try other cheap fixes before replacing either of these pricey things!
     
    #4 CLCL, May 9, 2024
  5. ChapmanF

    ChapmanF Senior Member

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    IV
    If a customer brings a car to me that has no symptoms of any trouble and no warning lights, and I say "hey, this had an actual brake problem, but I did cheap thing X and now it's fixed", who knows?
     
    #5 ChapmanF, May 9, 2024
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