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coolant heat storage (thermos), how do you test it?

Discussion in 'Gen 2 Prius Technical Discussion' started by stealthvw, Mar 10, 2008.

  1. stealthvw

    stealthvw Junior Member

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    I have a 06 that was in a front end collision. It was repaired but I get engine faults such as p1116 which are assoicated with checks of the coolant heat storage tank temperature sensor. I fear that the thermos has been damaged and is not really working. I suspect that this causes unexpected differences in the temperature sensor signal when the system compares the coolant temperature at the CHS tank and the engine coolant teperature.

    How is the CHS tank checked? I assume it should have "hot" coolant in it after sitting all night in the cold garage. When I open the drain valve I get cold coolant after sitting for 10 hours. ( This may be normal as the cold liquid falls to the bottom ).

    Is there a check out that will tell me if the tank is toasted.?


    I have a OBD2 PC tool that can read the coolant temp sensor on the engine and the temp sensor near the CHS tank.
     
    #1 stealthvw, Mar 10, 2008
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    In theory, DTC P1151 "Coolant Heat Storage Tank" is supposed to be logged if the tank outlet temperature during preheating is below 50 degrees C. An additional test is performed 5 hours after you turn the car to IG-OFF, and if the outlet temperature is more than 30 degrees C below the temperature logged during coolant recovery, that DTC will be logged.

    So if you don't have P1151, the coolant tank is supposed to be OK.

    What other DTC codes besides P1116 do you show?
     
    #2 Patrick Wong, Mar 10, 2008
  3. stealthvw

    stealthvw Junior Member

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    I also get P1150. I don't recall ever getting P1151 but I can check my notes later this evening.

    I would like to be the sensor in the tank if at all possible or even the bypass valve. These are much less expensive.

    Any ideas in a good check of the tank?
     
    #3 stealthvw, Mar 10, 2008
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    DTC P1150 Coolant Path Clog Up implies a problem with the tank outlet temperature sensor, the water valve, clogging in the system, or the engine ECU (ECM).

    The repair manual does not provide a spec for how long coolant should remain at a particular temperature. I don't have suggestions regarding how to check the tank beyond relying on the ECM to log P1151 if the tank has a problem.

    Since P1116 and P1150 both point to the tank outlet temperature sensor, assuming you have no other related DTC, I suggest changing the sensor first. It seems you have sufficient evidence to diagnose the sensor as the failed part.

    In your first post, you mentioned that you can read the temps of the engine coolant and the coolant tank as reported by the OBDII port. What readings do you get? Do those readings correspond closely after the car was driven and the coolant tank has been filled with hot coolant? If so, maybe the sensor is OK.

    The manual indicates that the sensor resistance should be 2-3K ohms at 20 degrees C and 200-400 ohms at 80 degrees C. It also suggests using an infrared thermometer to read the tank outlet temperature in the vicinity of the sensor.
     
    #4 Patrick Wong, Mar 10, 2008
  5. statultra

    statultra uber-Senior Member

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    the temperature sensor or something might be bad. im not sure about the thermos though.
     
    #5 statultra, Mar 10, 2008
  6. stealthvw

    stealthvw Junior Member

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    I plan on capturing the temperature data when I start up and drive 8 miles to work Tuesday. When the car was put in the garage tonight we had driven 30 miles or so and the engine should have been fully warmed up and the tank should be hot.

    If all goes well, I should be able to post the screen capture video while I drive and warm up. The tool does not record data for the prius specific PIDs but it displays the data. You can see the water flow valve comming on and off and the temperature changes on the tank output temp sensor. The water flow valve only connects the tank to the rest of the system durring the pump activity and for about 20 seconds while the engine is hot. ( at least that is what I see my car do ).

    I have not had other DTCs. The strange item is that they come and go self clearing. It may be an indication of a wiring issue to the sensor since it would seem strange for the sensor to be intermittant.

    If I can find the Part Number of the sensor I might just change it out.
     
    #6 stealthvw, Mar 10, 2008
  7. wyounger

    wyounger New Member

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    Are you sure the entire cooling system is fully purged of air, etc? It's gotten to where it can be tough to get all the air out of some cars. Did you just get it back from the body shop, or has it been like this for awhile?

    I would be curious to drive it until hot, put it in Park, and have a helper turn the car off while feeling the hoses connecting the thermos. Is hot coolant going in to it in the first place? Do you hear the coolant transfer pump running at the times you expect?

    To me the right way to check the heat storage ability of the tank is to confirm hot coolant going in, then fire up the Prius a few hours later and see if you can feel hot coolant going out of the thermos again.

    P.S. The transfer pump in my 07 is dying a slow, grindy-sounding death, but it still working.
     
    #7 wyounger, Mar 11, 2008
  8. galaxee

    galaxee mostly benevolent

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    well, that's how you test it alright.

    you still haven't ruled out the coolant control valve. if there is no hot coolant in the tank after 10 hours, it might not be getting there. properly stored coolant will still be hot enough to scald you after an overnight sit. if there is no hot coolant, of course the sensor reading is going to be low.

    run the car until it's hot, park it, let chs pump run its cycle. crack the valve on the chs tank. if the coolant is hot, the chs tank is bad and is not keeping coolant hot overnight. if the coolant is cold, the valve is bad and no hot coolant is getting in there in the first place.
     
    #8 galaxee, Mar 11, 2008
  9. MR.K

    MR.K Junior Member

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    Re: Dented Tank along I-80

    I just got a 2008 rebuilder in N.J. banged in the nose...How are these tanks made inside ? A glass liner on the inside? Are they pretty tough? If the tank has some small dents could it still be OK? ...Also..I need to find some one who has a frame machine along I-80 as my rails are over an inch ...I live in Idaho....fly back...then....gonna try to patch it up ...drive it home ...thanks all
     
    #9 MR.K, Mar 16, 2008
  10. maseace

    maseace Prius enthusiast

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    Anyone have experience with DTC P2601, which is supposed to be the Coolant Heat Storage control circuit? I have gone through the repair manual and checked the wire harness, CHS water pump relay, CHS tank outlet temp sensor, and CHS pump. All measurements were within range at ambient temp. Is there a way to directly test the CHS water pump? Maybe directly apply 12V DC to the pump connector? I'm not sure what voltage the pump operates on. I get the P2601 code every time the car cools off completely, when turning it on for the first time each day. The dealer thinks power is not getting through the wire harness, but I verified each wire from the sensor to the ECM.
     
    #10 maseace, Aug 30, 2008
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    #11 Patrick Wong, Aug 31, 2008
    SFO likes this.
  12. Mr.Sparkle

    Mr.Sparkle Junior Member

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    Hello

    Using and OBDII scanner, which PID or value corresponds to the temperature sensor of the coolant heat storage tank?

    Thanks
     
    #12 Mr.Sparkle, Mar 20, 2019
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