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Prius 'Hybrid System Warning' light on and off

Discussion in 'Generation 1 Prius Discussion' started by Swise, Nov 13, 2016.

  1. Swise

    Swise New Member

    Joined:
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    Sydney Australia
    Vehicle:
    2003 Prius
    Model:
    I
    Hey guys,

    Wondering if you could help me out with my Gen 1 Prius that is playing up a little.

    First things first, I want to say it is driving as it always has, and never skips a beat. No performance issues, sluggishness etc.

    A few days ago we noticed the Red Triangle and the far right 'Hybrid System Light'. Took it to a Toyota dealer, they plugged in for free and told me it's pointing towards the inverter being the issue. 150,000KM on the car, allot of it highway. This fault comes on and goes away by itself. Toyota have confirmed it is not my battery.

    Now the interesting thing here is that this has only literally just started 1500km after I took it to an independent that replaced both my engine coolant and Hybrid coolant. He did comment that it "wasn't easy". This makes me believe that he wasn't all that confident in changing it or he hasn't done it to spec ie, air in line etc.

    What makes me think there is an issue with cooling is that I have noticed the fan remaining on (whilst engine off) allot more often, I also noticed the Red high temp light very briefly come on, and go off the other day in not so hot weather, with the fan on, and this light has never come on before. I looked at the inverter coolant reservoir with the cap off and engine on and I cannot see any motion in there. On top it is full to the brim, well over the full mark. No bubbles, nothing.

    Am I looking at a simple case of just having the dealer replace the inverter coolant advising them to check the pump and properly bleed the system? Seems better than paying 4 hours of diagnostic as they suggested to eventually have them want to replace my whole inverter. Am I on the right path?
     
    #1 Swise, Nov 13, 2016
    Last edited: Nov 13, 2016
  2. greasemonkey007

    greasemonkey007 Active Member

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    Vehicle:
    2006 Prius
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    If you see no movement at all in the inverter coolant reservoir, that's a problem! Check the am-2 fuse to make sure it's good. Most likely the pump has failed. If so, have it replaced. The pump can be tested with 12V to check operation before assuming it's bad. Pump failure will lead to inverter and transmission overheating since the coolant is not being circulated.

    Since the coolant was just changed, I'd re-use it. Make sure that it stays clean and strain it through a paper towel as you pour it into an empty jug. The easiest way to get the air out of the system when filling it with coolant is to use a vacuum tool to pull the system into a vacuum before filling. I spent about $90 for an air tool that does that. Well worth it!

    After the pump has been replaced and coolant installed properly, check the reservoir again for swirling movement of coolant. If it's working now, you can check and clear away any fault codes and see if they return.
     
    #2 greasemonkey007, Nov 13, 2016
  3. ericbecky

    ericbecky Hybrid Battery Hero

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    Vehicle:
    2005 Prius
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    If you can get the fault codes read and then tell us what they are it would be helpful.
    It will (hopefully) identify what component of the car is failing.
     
    #3 ericbecky, Nov 13, 2016
    MDNHW11 likes this.
  4. Brian in Tucson

    Brian in Tucson Active Member

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    Pennywise and pound foolish! Paper towel is very linty--lots of little long strand paper fibers. Drain the new-old coolant into a jug and recycle it. Use new stuff--not likely to be contaminated. If you must go cheap, tho, don't go totally cheap, get one of those gold mesh permanent coffee filters, and after you've cleaned up the exterior areas of the engine/trans around where the drain is, run it through that and a nice clean funnel.

    And take the Prius to a Hybrid mechanic for servicing if you can't carefully read up and do it yourself.
     
    #4 Brian in Tucson, Nov 14, 2016
    Last edited: Nov 14, 2016
  5. Swise

    Swise New Member

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    Location:
    Sydney Australia
    Vehicle:
    2003 Prius
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    I
    Hi guys. Thank you so much for your help. Just updating you guys I had the pump replaced and the DTC has not returned. The original dealer did not provide the code to me as it was done for free.

    Looks like I saved myself allot of diagnostic fees and replacing a new inverter which is what the original wanted to replace.

    Feels good to save money.

    Over and out.
     
    #5 Swise, Nov 25, 2016
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