How can I monitor the transmission temp?

Discussion in 'Gen 3 Prius Technical Discussion' started by Higgins909, Jan 8, 2021.

  1. Higgins909

    Higgins909 Member

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    I have a Scangauge 2. I have MG1 and MG2 and maybe the inverter MG1 and MG2 added. It doesn't really explain what these are. I'm trying to monitor transmission temps, as I've been thinking about possibly pulling a trailer. I wanted to get some baseline temps while it's cold and then when it warms up. (might be doing it around May or so)


    Thanks,
    Higgins909
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    MG1 and MG2 (in the context of temperature data sources) are the motor-generator windings. They are what take the most thermal abuse in the Prius transmission, so that's probably what you ought to read.

    There is no valve body and the ATF never bears the pressure of moving the car nor cools a clutch as in a traditional transmission, so heavier loads doesn't give as much extra heat.

    Don't let that trick you into thinking you can tow that much. The car's brakes give you about 1000lb of payload to play with, whether it's in the car or dragged behind.
     
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  3. jerrymildred

    jerrymildred Senior Member

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    It seems like everyone focuses on the transaxle and forgets the brakes. There is only one thing a car must absolutely be able to do and that is to stop.
     
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  4. Higgins909

    Higgins909 Member

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    Yes, indeed. I kind of want a small boat, depending how the year goes and if I get more into fishing. I will go for trailer surge brakes, if I can make sure I can wire the car for it. I found a newer video of a Prius (3rd gen?) towing a tandem axle trailer with a 01~ tahoe on it. Was doing 55mph~ and must have been modified in the least for that tongue weight, because it wasn't sagging too much.

    If the year goes well and I get more into fishing, I'll install a hitch and wiring and rent a trailer and try to take it to a scale and do some benchmarks or something. To make sure before I buy a boat I can't tow. I'm not 100% sure, but I did front pads in Nov-Dec 2020 and thought they were similarly sized to a 06-08 Dodge Ram 1500's. But for sure the rotors are different sizes. My dad told me it was rated to tow like 10k or something a long time ago. I think I only found it rated at 7.5k or so. I was thinking the Regen and B mode would help, over a normal car like a civic or corolla.

    I know you're supposed to double or triple you're following distance, when towing. If I actually do it, I will be in the slow lane, probably letting everyone pass me, so I can keep a safe braking distance. Well, maybe I will actually be doing the 2 second gap thing. Around here, Austin, Texas, it's normal for people to be 10ft away going 80mph on the highway, even people towing...
     
  5. Mdv55

    Mdv55 Member

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    Pad size doesn't really dictate braking performance. It's the rotors and heat dissipation capacity that are more critical when it comes to heavy, repetitive braking.

    The Prius relies a lot on regen braking and has fairly small rotors to save weight.
     
  6. Georgina Rudkus

    Georgina Rudkus Senior Member

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    Any aftermarket transmission temperature gauge will work. Depending on the sensor's threading, a bushing will be needed to adapt that thread to M18x1.5, which is the straight threaded drain plug size for the transaxle.
     
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