New problem - heater, tech stream and dash interface

Discussion in 'Gen 2 Prius Technical Discussion' started by Bart47, Dec 11, 2020.

  1. Bart47

    Bart47 Junior Member

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    Ok, I thought I was in the clear after seemingly getting my battery problems behind me, but I have still not successfully made a real point a to b trip in a Prius yet... Tried today to drive to the closest local town, but it was about 40 degrees, so I turned the heater on. When I got this car, the combination meter was bad and then I had to replace the dash monitor with one from my parts car. The original one worked for a while, and I saw how it was set up with all the options for display - it was awesome. The one I replaced it with was pretty std, just has the 4 buttons, and limited on the info, so that is one thing, don’t even know why I mentioned it, but I was able to get into the climate settings and set the temp up high enough that it should have sent the proper request for hot air to be sent, you know, the actuator doors to be opened and fans and valves and such. Anyway no hot air. Unfortunately, I was on a bad stretch of 2 lane road with no good place to turn around. So my round trip was probably 8 miles, farther than I should have taken it, without knowing if it was overheating, like a with a thermostat not opening, or something. There was no light or warning that it was, just made me uncomfortable not knowing. Anyway, when I got home, I opened the hood, and nothing smelled hot , nothing even felt hot, which seemed weird, though I don’t remember touching the hoses, (which would have made the most sense)... I did open the radiator cap, and it was fully pressurized, as it it sprayed a fairly good amount of antifreeze around when I opened it. But, oddly, the fluid that got on my hand wasn’t excessively hot at all. Kind of weird for the kind of pressure...and something similar had happened the other day when just drove it around the “block”, not even long enough to get up to operating temp, but I checked the fluid, and it was pressurized just like today...so I was trying to research some other posts before I put this up, and I saw one talking about 3 different conditions to check to determine what a P1121 code really meant, (I haven’t checked my codes yet, waiting for my old laptop to charge up), but it said that with Techstream, you can watch it while it heats up, so you can identify what condition you are really dealing with... how do you use Techstream like that? I haven’t seen how to do that kind of dynamic testing, can someone lend me a hand in understanding that, as well, please? Thanks very much!
     
  2. ChapmanF

    ChapmanF Senior Member

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    If you're saying you have Techstream, you can go to the Engine Control Module, and select Data List, and one of the numbers you can watch is the coolant temperature, and watch that rise as the engine warms up. (For my Gen 3, I think the 'stat is supposed to begin opening around 80 to 84 ℃ and be fully open by 95℃; Gen 2 might be a little different but in the ballpark.)

    You can also go to the Air Conditioning controller and view its Data List, and you'll see what it thinks the cabin temperature is, and what it thinks your desired temperature is, and what it's planning to do about it. Or you can go to the Active Tests and move the different air doors around, turn the circulating pump on and off, and so on, if you have any doubts about any of that.
     
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    So you replaced a 7 button MFD with a 4 button? I've always heard mixing models was a big no-no. The model number of the MFD that was original equipment is the only one that should be used as a replacement. It can be done sometimes if you correct the wiring positions using a good wiring diagram, but just doing a direct swap with different models?...I've heard is a good way to spend a bunch of extra time chasing ghosts...……….you're assuming the 4 button MFD uses the same wiring/signal layout as the 7 button. I'm thinking, (no, lets correct that, I'm telling you) that's a bad assumption. I have two test harnesses I use to test MFDs. The 7 button MFD gets power on different pins than a 4 button MFD. I accidently plugged the 4 button MFD test harness into a 7 button MFD once and only ONCE, as the loud popping noise and smoke helped me learn a valuable lesson.

    I did open the radiator cap, and it was fully pressurized, as it sprayed
    I don't want to be mean, but wow, that could be pretty damaging...…..
     
    #3 TMR-JWAP, Dec 11, 2020
    Last edited: Dec 11, 2020
  4. PriusCamper

    PriusCamper Senior Member

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    An 8 mile round trip is no where near long enough to figure out if you're heater is working... And if you're taking off radiator caps without the car cooling off, I bet you probably have some scary hybrid battery repair stories as well. :)
     
  5. Bart47

    Bart47 Junior Member

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  6. Bart47

    Bart47 Junior Member

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    In retrospect, I can totally see your point that only an idiot would take off a hot radiator cap. However, I must have failed to convey that it was not at all hot either time, and I had thought the pressure was the pump had built up a small amount of pressure from not being able to properly flow through the entire system, as in a stuck thermostat. I have since re-thought that, but never mind, I’ll figure it out. Thanks to those who have made a good faith attempt to be helpful.
     
  7. PriusCamper

    PriusCamper Senior Member

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    If you can let us know how the heater works after 1/2 hour of driving, preferably at freeway speed that'd be key. Also if you have problems with getting Toyota Techstream going, the Hybrid Assistant and it's companion Hybrid Reporter app can grab all your water temp data for you. Just need to buy an inexpensive OBD2 to connect your phone to the car. Here's a buyer's guide: Hybrid battery diagnostic and repair tool for Toyota and Lexus
     
  8. Bart47

    Bart47 Junior Member

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    Thank you. I was able to view the live data aspect of Techstream, so that was very helpful. Before that, the heater did start working, and one of the codes that came up was a stuck valve, forget right now which one, but once I cleared it, it did not come back. I don’t have complete confidence that it won’t, but I imagine it can be explained by the car sitting for as long as it has. I intend to replace the valve, and ease into using the vehicle regularly, in case there are other latent problems waiting to rear their head, but happy at the moment, at least.
     
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  9. dolj

    dolj Senior Member

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    Was the stuck valve the coolant control value, by any chance?

    You can use Techstream to command that valve to any of its positions to verify in which position it is sticking. The code for that is P1121.
     
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  10. Bart47

    Bart47 Junior Member

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    Thanks, I will try that.
     
  11. mr_guy_mann

    mr_guy_mann Senior Member

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    The cooling system wasn't hot, it was merely warmer than it was earlier. The radiator cap is designed to trap pressure inside the cooling system until it exceeds the cap's opening pressure. So as you run a cold engine, the cooling system is closed- any heat added from the ICE causes that "trapped" coolant to expand some- building pressure. I usually give to upper radiator hose a squeeze to see if there is any pressure built up before trying to take the radiator cap off.

    If your thermostat fails in the closed position, it will cause the engine temperature to go too high (dash warning lights, boil over, eventual engine damage, etc. It can happen but it's pretty rare. (less than 5% of all the thermostat problems I've ever seen)

    More common is where the thermostat either; fails to close completely, or opens early- this causes slow warmup, low heater output temps, poor MPG, oil sludging up, ECM inspection monitors not running, etc.
     
    #11 mr_guy_mann, Dec 12, 2020
    Last edited: Dec 12, 2020
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