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P1121 replaced pump still get the code

Discussion in 'Gen 2 Prius Technical Discussion' started by Dave Jeffries, Jun 15, 2024.

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  1. Dave Jeffries

    Dave Jeffries Junior Member

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    Last August I bought a Genuine Toyota Coolant Control Valve 16670-21010.

    I installed the valve and reset the codes. That lasted for several months. Now the check engine light will come on and after several days go off. Using the scanner, P1121 code was set. I clear the codes.



    What else in this system can be setting the code? I would hate to think I got a bad genuine Toyota part.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    I would hate to think that too but I don't think these parts that we're buying are new old stock I think they're still making coolant control valves cool and heat storage tank pumps the pump that's in between the brake actuator and the other part on the firewall near the pedal and electric water pumps for the generation 3 break actuators for the generation 2 I think all that stuff is still being made to keep up with the demand for the supply so the modern manufacturing processes are going into the new manufacturing of these older parts that we've always depended on and we're good now the new processes and the cheap materials are going into our once well-made parts I have to think this is what's happening they're not going to keep making the part the old way with more solder and more copper and good quality like they used to they're going to do things the way they do them now they're where the highway you know the routine and so here we are things are failing a lot sooner we accept it because that's how the new generation of folks coming online are remember our kids and stuff they've been trained by not us but the world that 150 K is a good run for a vehicle You should get out of it quickly and go get another loan or spend your money and get another one That's just the way you do for my 50 some odd years I've been getting two $300 400,000 so I kind of spoiled and expected oh well
     
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  3. ChapmanF

    ChapmanF Senior Member

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    The P1121 code doesn't necessarily tell you "replacing this valve is what you have to do." Before there could be any such thing as a trouble code that tells you what to do, there would need to be some way for the computer in the car to figure out why it is seeing the inputs it is seeing, which of course it can't. So any trouble code can only be telling you about what the computer in the car is seeing, leaving it for the human to figure out why.

    What the computer saw when it stored a P1121 will be one of these things (this is what you find in the "detection condition" box when you look the code up in the repair manual):

    • The valve's position sensor output voltage didn't change, or changed too slowly, when the computer was signaling the valve to change position, OR
    • the temperature reading at the thermos outlet was 60 ℃ or more already when a hot-coolant recovery operation started, OR
    • during a hot-coolant recovery operation, the temperature reading at the thermos outlet didn't change..

    So, when you look at a diagram of the system, you can think of various things that could be wrong and cause the computer to see one of those things and store the code. A bad valve is only one of them. In fact, if the code is still around after changing the valve, that might suggest the valve never was the problem in this case. (Or, it could have been the valve that time, and this time could be different.)

    There are about four pages of troubleshooting ideas in the repair manual to help pin down what the root cause is so the right fix can be made.

    Toyota Service Information and Where To Find It | PriusChat
     
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  4. Tombukt2

    Tombukt2 Senior Member

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    Yeah I thought the coolant heat recovery tank output or whatever would be involved in this so if you've already replaced the coolant control valve then you start looking at the CHS business however it is or isn't operating The temperature sensor's bad or the pump's not pumping One of the two will cause this funny business to go on and if you've put a real Toyota threeway control valve in more than likely that is not the problem again.
     
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  5. Tombukt2

    Tombukt2 Senior Member

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    On a funny note a friend of mine called me today quite concerned said he thinks the coolant heat storage tank pump is making a horrendous racket it sounds worse than the break actuator when it's failing and it is loud from what I can hear on the telephone I told him to check and make sure it's not pumping nothing. But I have several CHS pumps off and we can change it pretty quick haven't heard back but over the phone the thing sounded horrendous unbelievable this is the same pump that I use for my inverter pump now mine you can't even hear it running either my chs or the CHS doing inverter duty. Seriously very quiet You have to put your hand on mine to even know they're running but the water's moving and everything's wonderful.
     
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  6. dolj

    dolj Senior Member

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    I thought you said a while back that you repurposed the pump that sits against the firewall behind the inverter and up from the brake actuator for your inverter pump, no? Now you're saying you repurposed a CHS pump?
     
  7. Tombukt2

    Tombukt2 Senior Member

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    They're both the same style pumps One is a 14.1 volt marked pump and the other one is 12 volt I believe the 12 volt is inverter pump duty in the 14.1 volt pump is the one between the brake actuator and the other piece on the firewall for the brakes You are correct mine is the 14.1 pump then I removed some CHS pumps because I thought I had one or two failing on one or two cars here and apparently I have a customer who has one failing right now it's making a lot of racket but yes mine is the one from higher up in the car behind the inverter literally The CHS pump that I did try to use for the same duty as the inverter pump the 12 volt pump didn't last very long I'm not sure why The 14.1 volt pump from between the two break pieces has been in now I don't know two and a half or three years but both of those two pumps look identical look like a little tiny might spa pump tiny might as a brand name actually.
     
  8. Tombukt2

    Tombukt2 Senior Member

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    And this is only in the '09 original generation 2 Prius that we purchased at the very beginning of the pandemic All the other generation twos here have the original pancake pump doing inverter duty. None of them have gone bad acted up done anything so just left them alone I've got one with a bad CHS tank pump that I need to replace and I need to check it sensor too.

    And I found this other little 12 volt pump with the right hose barbs on it 12 volt doesn't have the same plug as the Prius for the inverter pump and I've used it on a couple of motorcycles and scooters that are water cooled like a $52 pump and it's MAG drive and all that and looks like it'll probably hold up 15 20 years and it is small The impeller size is about the same size as what's on the stock inverter pump but the rest of the pump body is maybe a 2-in diameter at best way smaller than I'll try to take a picture of it when one of the other inverter pumps breaks I'll try this pump because it's so small doesn't even require a bracket it'll just hang on the hoses that it's plugged into and that's it weighs nothing.
     
    #8 Tombukt2, Jun 17, 2024
    Last edited by a moderator: Jun 17, 2024
  9. mr_guy_mann

    mr_guy_mann Senior Member

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    Was that a "genuine from a dealer" part? Or was it a "(maybe) genuine from the internet" part?

    That said, most times this code results from electrical faults in the valve itself. (I have had to use a scope to "see" the fault).

    However, I have also seen problems with the CHS pump or the CHS temperature sensor.

    Really I usually recommend that you use a capable scantool to monitor CHS temperature during a "cold start" - see if the pump runs just before the ICE starts. Does CHS and engine temperature increase?

    But no one actually does that.

    Good luck.

    Posted via the PriusChat mobile app.
     
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  10. dolj

    dolj Senior Member

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    So all of that is to say, "Yes, I did repurpose the pump that sits against the firewall behind the inverter and up from the brake actuator for my inverter pump (the pump that supplies coolant to the heater core when the engine is not running) but the socket was wired differently so I had to rewire the connector to use the said pump."
     
  11. Tombukt2

    Tombukt2 Senior Member

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    Yep I make a jumper from the old connector to the pump that goes there the pancake to the new plug that goes to the spa looking pump so that I can go back and forth to whatever I want whichever pump and I just found another pump that looks like it'll work even better and is smaller and quieter I've used it on a couple of my motorsports scooters that are water cooled obviously