Intermittant Trouble Starting Hybrid System

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by labumm, Jan 4, 2005.

  1. labumm

    labumm Junior Member

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    Ever since I brought the car home I have VERY occasionally had trouble getting the hybrid system to start. Here is the scenario.

    1) With foot on the brake, press the ON button.
    -- Only the display comes on, ON button LED green.

    2) With foot on the brake, press the ON button AGAIN.
    --The dash lights, environmental controls come on, no READY light, ON button LED amber.

    3) With foot on the brake, press the ON button AGAIN.
    --The car turns OFF.

    A clue is that this is EXACTLY what happens when you don't have your foot on the brake.

    The week before Christmas this really started acting up. About half the time I would experience this problem. Sometimes it this would go on for 10 minutes. (How many times can you start your car in 10 min?)

    I knew about the break-light switch recall, so I mashed the break pedal. Sometimes this seemed to help. Finally this happened at night--NO BREAK LIGHTS! The when the break lights eventually started to work, the hybrid system would start normally!

    Fortunately my dealer had already ordered 40L before this started. I took it in as soon as I could and 40L seems to have cured the problem.

    This makes sense because the two systems use the break-light sensor.

    The moral of the story: If this is happening to you, get 40L.

    Why me? I have one of the early 2004's; the VIN is pretty close to 4000. Hence I will have one of the older 2004's with the early parts.

    --LAB

    **Note that this behavior is not the same as the 'stuck in IG-ON' condition reported at this site.
     
  2. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    What is the timeframe between steps 1 and 2? Is it possible that you are not pressing the button twice fast enough. For me, I thought it almost barbaric to punch the button twice so quickly, so I would almost casually press it twice if almost elegantly. Sometimes, being so slow would not put me into [Ready] mode.

    Just a thought.
    (And another piece of the complicated Tony puzzle. And just to mix things up, keep in mind that not all the pieces belong to the same personality. :-D)
     
  3. labumm

    labumm Junior Member

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    1/2 sec to over 10 sec. No difference. With the brake working it will go into [ready] mode (hybrid system on) from either the post 1 or post 2 states.

    If you push the ON button twice too rapidly the deglitching circuit will make it act like it was only pressed once. That is to overcome the short comings of mechanical systems like switches.

    --LAB
     
  4. labumm

    labumm Junior Member

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    The psychology of the problem is interesting. While it is happening, you know (hope) that this is an intermittant problem and that it will just fix itself. But mindlessly pushing the button over and over, varying the way you push it, etc. is like standing alone in front of a soda machine, checking the coin return every 10-15sec to see if there is change in the coin return. If there was no change the first time, maybe it is there the second time, third time....

    I am quite acustomed to troubleshooting all manner of equipment, experiments, etc. Usually one has a model in mind to guide ones actions. Here we have a button that appears responsive and a foot pedal. Its just damn unsatisfying to keep pushing that button and not getting the [ready] light. Then magically, after no appearent change ion procedure, it works.
     
  5. Frank Hudon

    Frank Hudon Senior Member

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    no brake lights, no start. It's as simple as that. If this happens to you out in the wilderness take a paper clip, bobby pin, staple, what ever and bypass the brake light switch. It'll get you going.
     
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