Ongoing Combo Meter Hell

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by seth.7, Mar 28, 2017.

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  1. seth.7

    seth.7 New Member

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    My 2005 Prius died a number of times in the last two months because it apparently was not turning off when we hit the power button.

    I took the aftermarket battery to have a charge capacity test and it came back as working fine.

    So it "seemed obvious" that it was the combo meter. Given that I could buy a rebuilt combo meter off ebay for the price of a diagnostic around here, I bought one and installed it myself, because who wouldn't.

    However I am screwed.

    The car would not start. If pressing the brake, nothing happened. If not pressing the brake, I would get the power light on green, a flashing light on the park button, and nada else other than the door open light up next to the combo meter.

    So I took it all apart again, checked all the connections (from memory: two ribbon cables and two white connectors, one large one small on the combo meter; above steering wheel: two white connectors and one single wire grey connector, power button connector, park light connector in the air vent piece, two white connectors at top of center display unit and two connector at the bottom of it; one speaker cable above center console; one airbag connector on passenger side). Same deal.

    Took it all apart a third time. reinstalled original combo meter which was working, just quit every once in a while. No change in symptoms, ie:

    The car would not start. If pressing the brake, nothing happened. If not pressing the brake, I would get the power light on green, a flashing light on the park button, and nada else other than the door open light up next to the combo meter.

    Obviously I am triple checking every connection every time, and I don't like tearing everything apart so many times, because these connectors are not the strongest.

    As background, I feel competent to do this, I have done many pc and laptop repairs, arduino builds, random electronic repairs, car repairs, etc.

    What next?
     
    #1 seth.7, Mar 28, 2017
  2. andrewclaus

    andrewclaus Active Member

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    What is the no-load voltage of the 12V battery?

    When my CM failed, I was always able to start and drive the car, and able to stop it with a 3-second push of the power button. I hear that's the usual case.
     
    #2 andrewclaus, Mar 28, 2017
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  3. edthefox5

    edthefox5 Senior Member

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    I'm with Andrew...in the morning before you start the car open the hood open the black fuse box and at the jump points measure the dc volts.

    And I hope your disconnecting the 12 volt battery when your swapping the CM. It serves 2 proposes...one to protect you from stupidity and the other is a fresh reboot of the car when complete.

    Not necessary to unbolt the negative battery cable just take the red plastic cover off the post post assy and there's 2 black cables a big black one... that's main 12 to the front fuse box and the little black one which is 12 volt monitor to the converter circuit in the Inverter. Press the white plug clips and pull them out. Same as unbolting the neg cable but no sparks.

    If the 12 measures good anything over 12.2 then you probably blew a fuse.
     
    #3 edthefox5, Mar 28, 2017
  4. seth.7

    seth.7 New Member

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    My battery was at 12.8 V last test. I will check fuses and disconnect battery and let you know where we are at.
     
    #4 seth.7, Mar 28, 2017
  5. andrewclaus

    andrewclaus Active Member

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    And if you're working around all those airbags without disconnecting the 12V battery, you should read up on the subject.
     
    #5 andrewclaus, Mar 29, 2017
  6. JC91006

    JC91006 Senior Member

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    I would disconnect the 12v and try and reset the car. A bad brake lamp switch under the dash would prevent your car from going READY when pressing the brake.

    If you only disconnected the dash area, there's really no reason your car won't go READY
     
    #6 JC91006, Mar 29, 2017
  7. seth.7

    seth.7 New Member

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    OK, so it was a battery issue. I had checked voltage 2 days earlier and it was fine, and car was "off" for those two days, but somehow battery was dead. Other than the extended store test of battery health (which I did) and just waiting, is there any way I can proactively try to verify whether I have dealt with the battery drain issue? I did have a problem with the combo meter not dimming, which is fixed with the new one, as well as an issue with the headlights not turning off when turning off from aux mode (also fixed) - so perhaps I made the right guess.
     
    #7 seth.7, Mar 29, 2017
  8. andrewclaus

    andrewclaus Active Member

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    You can check your "parasitic draw" with a DC ammeter in series with the negative terminal and ground. If it approaches or exceeds 100 mA, you might have an issue. I'm not sure what "normal" is for a Prius, and SKS if you have it draws a larger load, but 100 is pretty high.
     
    #8 andrewclaus, Mar 29, 2017
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