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won't hold speed on cruise control.

Discussion in 'Gen 2 Prius Technical Discussion' started by Bob Holliston, May 1, 2018.

  1. Bob Holliston

    Bob Holliston Junior Member

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    The other day I was on the freeway coming up a hill and the C/C wouldn't hold the speed going 74, like not enough power. Never happened before on that not very steep hill. I messed around floor boarding it and there was defiantly a problem which lasted for 10 minutes or so. Hasn't happened since. What's up with that? (2009, 125 K miles).
     
    #1 Bob Holliston, May 1, 2018
  2. bisco

    bisco cookie crumbler

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    headwind?
     
    #2 bisco, May 1, 2018
  3. dolj

    dolj Senior Member

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    Could also be the HV battery getting lower in capacity to the point where the ICE (internal combustion engine) cannot compensate.

    Was the ICE racing higher than normal?
     
    #3 dolj, May 1, 2018
    Mendel Leisk and Beachbummm like this.
  4. fotomoto

    fotomoto Senior Member

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    Losing CC function completely was one symptom I had when the HV battery was failing but hadn't thrown a code yet.
     
    #4 fotomoto, May 1, 2018
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  5. Bob Holliston

    Bob Holliston Junior Member

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    No headwind, battery's the best guess but with only 135 K miles? There WAS a problem as the top speed (normally 103 MPH on the flat) was down to about 80, hammer down and there seemed to be some "surging". It seems OK now, but I REALLY hate intermittent problems like this. Thanks for the replies.
     
    #5 Bob Holliston, May 2, 2018
  6. jerrymildred

    jerrymildred Senior Member

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    Sounds battery related. Does the battery indicator on the MFD change more quickly than it used to? That's one way to know yo've lost capacity. If you recondition it with a grid charger, you can likely buy yourself enough time to finish wearing out the rest of the car.
     
    #6 jerrymildred, May 2, 2018
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