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09 Prius coolant flow valve code 1121 Please help

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Joekingiam, Nov 7, 2013.

  1. Joekingiam

    Joekingiam Junior Member

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    I have read all the posts pertaining to this code, replaced my coolant flow valve, bled all the air out of the coolant system and still am getting the cel with the 1121 code.
    I have tried setting multiple coolant flow valve positions, checked all wiring in harness, coolant level is full in rad and reservoir, checked temp sensor at bottom of storage tank, checked pump operation at top of tank to attempt to clear this code to no avail.
    Is there a default position the valve is to be in before cold start up?
    Is there anything else that can trigger this code? What am I missing?
    I appreciate all your input.
    Joe
     
    #1 Joekingiam, Nov 7, 2013
  2. Joe 26

    Joe 26 Member

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    Does the cabin heater blow hot air? If not, then you are still low on coolant, that can set the code. It is very difficult to get all of the air out of the cooling system.
     
    #2 Joe 26, Nov 7, 2013
  3. razdan

    razdan New Member

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    Sometimes you need to drive the car around a bit to get the coolant running through the system.
    Once you drove it for a bit then try beading it out. that has helped me int he past.
     
    #3 razdan, Nov 7, 2013
  4. Zedhomme

    Zedhomme Member

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    Have you gotten any Temperature Warning Light? If not, the coolant may not be low, but it does help to take it up to full operating temperature with the heater on HIGH temp to make sure all air is bled.
    Did you flush the radiator when you changed the valve or just clamp off the hoses to minimize coolant loss? P1121 can also be clogged passages.
     
    #4 Zedhomme, Nov 8, 2013
  5. Joekingiam

    Joekingiam Junior Member

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    #5 Joekingiam, Nov 9, 2013
  6. Joekingiam

    Joekingiam Junior Member

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    My heater is producing heat no problem
     
    #6 Joekingiam, Nov 9, 2013
  7. Joekingiam

    Joekingiam Junior Member

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    Hello, I do not have any warning light. I flushed radiator. I am not sure about clogged passages or how I could determine that there is one. I am at my wits end.
    Joe
     
    #7 Joekingiam, Nov 9, 2013
  8. Joekingiam

    Joekingiam Junior Member

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    Is there a default position the valve is in at start up when cold? or hot? What sends the power/signal to this valve? How can I know that the valve is operating?
    I still cannot rid myself of this cel light.
    I appreciate your input.
    Joe
     
    #8 Joekingiam, Nov 26, 2013
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The valve is supposed to allow fluid to flow to the coolant heat recovery canister, upon startup.
    Clogging in the cooling system or a failed ECM are the other two reasons for DTC P1121 (besides a failed engine coolant valve.) Check the wiring harness connector to the engine coolant valve as well as the connector to the coolant heat recovery tank outlet temperature sensor. Obviously, you need to be sure that the hoses are correctly connected to the engine coolant valve.

    Did you notice any contamination or foreign matter in the drained coolant? If no, then you probably don't have clogging in the cooling system.
    The ECM controls the engine coolant valve. A potentiometer within the engine coolant valve moves as the valve changes position. The ECM tracks the resistance provided by the potentiometer, which enables the ECM to decide which of the three possible positions the valve is in. The ECM also tracks the coolant temperature at the outlet of the coolant heat recovery tank.

    Here are the specific reasons that DTC P1121 would be logged by the ECM.
    Water valve position sensor output voltage: No change despite the ECM sending a valve control signal or slow response
    CHS tank outlet temperature sensor output: 60C (140F) or more (when hot coolant recovering starts)
    CHS tank outlet temperature sensor output: No change despite the hot coolant is recovered
     
    #9 Patrick Wong, Nov 26, 2013
  10. Joekingiam

    Joekingiam Junior Member

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    Hello,
    Thanks for your reply, I checked and there is no clogging, I also checked output changes on tank coolant sensor and it seems to be working.
    If I do need another ECM, where is it located and can I swap this out easily myself with a used one or does it need a new one programmed through dealer?
     
    #10 Joekingiam, Dec 3, 2013
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    At this point I suggest you download repair manual info at techinfo.toyota.com

    I believe that the ECM can be swapped without programming. However that is the least likely problem so I would encourage you again to carefully check all of the other possibilities first.
     
    #11 Patrick Wong, Dec 3, 2013
  12. Joekingiam

    Joekingiam Junior Member

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    Thanks for your reply Pat,
    I saw something in a post about an ECM that has to be "flashed"? I hope I do not need to change it anyway.
    I am now going to disconnect the plug at the ECM and check continuity to the coolant control valve plug.
    Also I noticed I have not heard the coolant tank pump ever turning on. I did the relay paperclip jumper test and the pump works fine. I suppose that tank pump is not coming on because the coolant flow valve is not working either?
    Let me know
    Joe
     
    #12 Joekingiam, Dec 4, 2013
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