Transmission Temp Gauge install w/pics

Discussion in '80-Series Tech' started by Brian894X4, Apr 6, 2008.

  1. 96r50

    96r50

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    Using this thread as inspiration, I have spent the last 8 months (ok, I work slow :flipoff2:) trying to find a clean, easy solution for mounting a temperature sender in the outlet line of the transmission. I wanted the most accurate and timely representation of the heat in the transmission. I didn't want to cut or modify any of the existing hardlines or softlines (I'm picky like that) but I wanted as accurate a solution as possible. My first idea was to copy Tapage's tee fitting. However, after having zero luck finding the appropriate tee fitting that idea was scrapped. I also wanted the sender to be directly in the line of fluid, not in it's own little pocket off the main flow (I'm picky, right?).

    I spent some time looking at Wholesale Automatics' kits, I liked Rodney's idea of having the sensor installed in the line. Problem is, with the A343F, the outlet fitting is a cast piece with no space to add an extra sender
    [​IMG]

    One of the things I liked about Rodney's kit was the choice of gauge (you can see it in MiguelBlue's picture above). The VDO Vision series of gauges looks quite similar to the 80 series dash (white letters on black, red needle, green backlight), and I like keeping my projects OEM looking. The Vision series has three temperature gauges (Water, Oil, and Transmission). As Brian noted in his original post, the range on the Transmission gauge is pretty limited in the normal operating temperature range. I decided that that I liked the range on the Water gauge (80-120C), as a properly operating transmission should generally be in the same range as the coolant temperature. So I went to egauges.com and ordered the gauge, a 1/8-27NPT sender for the gauge, and an Acura Integra a-pillar pod (I followed boydmick's instructions to fit it to the 80 series).

    So at this point I had all the parts, but no plan. After some more time studying the EWD, FSM, and A343F manual I went and had a chat with the head Lexus mechanic (and good friend) at the local dealership. We concluded that the OEM ATF temperature sensor's only purpose is to set off the warning light on the dash when the fluid becomes (way, way, way!) too hot. It isn't tied into any other circuits according to any of the information we could find.
    Edit: TrickyT made a good point in a post below. I have included part of it here.
    We will never be able to tell for certain how involved the OEM ATF temperature sensor is or isn't in the ECU's logic. Since completing this install, I have not noticed any odd behaviour from my transmission, and I will certainly report back if I find anything amiss

    I figured that I will check the gauge often enough that I don't require a warning light (this ain't a soccer mom mobile anymore :D). With that in mind I went ahead with finding a way to replace the OEM sender with one for my gauge. I ordered the transmission outlet (shown above) and measured the threads on the sender port (M14x1.5). VDO does make a sender with the appropriate thread count, but the temperature probe looked way too long (from the photo on the egauges site, I never saw one firsthand). So I needed to adapt the sender I had to the outlet. (Edit: I have since ordered the VDO M14x1.5 80-120C temperature sender and mocked it up on my spare cooler outlet. No dice, the sender is indeed way too long to fit.)

    After a bunch more googling and hunting around, I found an adapter to mount my 1/8-27NPT sender in a M14x1.5 hole. 42DraftDesigns makes a number of custom CNC products for the VW/Audi market, and they had an adapter that seemed to fit my needs. I fired off an email with a couple very specific questions about dimensions and such and sat back. In under 24 hours I had a reply. Big thanks to John Pelton, the Sales & Shipping Manager at 42DraftDesigns for putting up with my incessant and sometimes nit-picky questions. He answered them all very promptly, and even took a number of photos of their adapter with the same VDO sender installed so I could see how it lined up. He provided some of the best customer service I have received from a vendor (especially for a vendor in a different market and therefore with nothing at stake in my project). Thanks John!

    The VDO sender, 42DD adapter and copper washer, and Toyota outlet
    [​IMG]

    Mocked up. The VDO sender does not affect the flow of ATF
    [​IMG]

    Showing the depth that the VDO sender will sit at
    [​IMG]

    So the hard part was over. I had all my pieces in hand. Install time was nigh! I combined this project with another (replacing the rusty ATF cooler lines mounted on the engine and under the DS headlight). During this project I confirmed that the forward line on the A343F (the one with the OEM sender in it) is indeed the transmission fluid outlet where the hot fluid leaves the transmission to be cooled. This is the temperature I wanted to measure, as it should be the hottest point. Things were working out!

    I removed the OEM ATF temperature sender (19mm open end wrench IIRC) and compared it to the VDO and adapter:
    [​IMG]

    The OEM sender in the OEM outlet. Apparently Mr T liked having the temperature probe right in the fluid (most accurate reading possible)
    [​IMG]

    Showing the depth that the OEM sender sits at
    [​IMG]

    Comparing the two senders, I had no fears about restricting the ATF flow more than the OEM sender did. I decided to use the O-ring off the original sensor instead of the copper gasket when I installed the VDO sender and 42DD adapter. If it was good enough for Mr T... I'm happy. I originally left the OEM sender off the truck, but my OD light flashed at me after 15 minutes of driving. I consulted the FSM and found that one of the transmission codes is in relation to no signal from the sender. I plugged the OEM sender back in and ziptied it up out of the way, and no more flashy light.

    I followed boydmick's instructions (linked above) to install the gauge pod. I ran all the wires down the A-pillar and connected the gauge lights to the rheostat, and used switched power from the gauge fuse to run the temperature gauge. The ground was the factory ground point in the driver's kick panel, and the sender line ran across behind the dash and down to the sender via the grommet in the transmission tunnel (in the perfect location) on the passenger side of the tunnel. The white tube in the photo is the line for the air pressure gauge that will tell me the system pressure in my soon-to-be-complete York OBA project.

    [​IMG]

    The gauges
    [​IMG]

    The driver's view
    [​IMG]


    I've had this installed for almost a week and have formed a good idea of what the temps tend to do. Cruising around the city in cooler weather (15C/60F) produces temperatures of 70C/160F. Working the truck hard today in hot weather (30C/85F) and driving some hills got the temp up to 90C/195F at one point, with it mostly sitting at 80C/175F. The stock ATF cooling setup performs admirably, with temps dropping rapidly when the load on the transmission is reduced (cruising the flats after a long hill, coasting downhill). I also noticed that while cruising the highway at a steady pace with the torque convertor locked up, the temps dropped about 10 degrees C (~15F).

    All in all, this is probably one of my top 5 mods in terms of usefulness and knowing how my truck is doing.


    Specific parts list:

    VDO temperature sender, 1/8-27NPT, 120C/250F = 323-095

    VDO Vision Black Engine Temperature Gauge Metric (40-120C) = 310-010-002K
    Same gauge in imperial units would be = 310-105

    42DraftDesigns Universal Oil Temp Adaptor - Drain Plug = 42-908
    (photo on the site is of old design, the one in my photos is the new, current design)

    :cheers:
     
    Last edited: Jul 30, 2010
  2. canman

    canman

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    Great looking mod! Looks like you took the time to make it as OEM looking as it could get (I'm picky like that as well - what colour did you use?). I will now have to add this to the "to do list". I will also be adding an OBA system, and never even thought of adding a press gauge in the cab:bang:. I am still accumulating the parts for the OBA system, but hope to have it installed in the next few months. Keep us posted on your progress:cheers:
     
  3. TrickyT

    TrickyT Hate that mud... SILVER Star

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    Hey, nice install Adam. Great OEM look to it. And nice writeup too - very thorough.


    Probably true, but really hard to say for sure. As you know, the A343F is electronically controlled by the ECU. The FSM documents at least most, maybe all, of the sensors and switches that the ECU uses for input for controlling AT operation. Obvious things are throttle position, vehicle speed, and shifter position. The EWD mentions coolant temperature too, but doesn't say how it uses this input for AT control. The ATF temperaure sensor isn't mentioned. My point is that it's hard to know with certainty that the ECU doesn't also use ATF temp in some way too. For sure it uses it to turn the combination meter idiot light on/off, but it could consider ATF temp when deciding to lock/unlock the torque converter too, since that would be an obvious way to lower/raise ATF temperature.

    Without looking at the computer program that runs in the ECU, we'll never know for sure. I think your conclusion about the ATF temp sensor only controlling the idiot light is reasonable, but you can't be 100% certain just because the Toyota manuals don't talk about it.
     
  4. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    Impressive post Adam ..

    One thing that come to my mind it's .. the ECU can lock the TC .. ? ( was thinking that was only posible by fluid pressure and rpms .. )

    When my 80 was automatic ( not anymore :D ) I was able to see 210°F max temps down here .. ( with outside temps of 100°F ) but in all cases it cools down ..

    The cruising speed at flat road don't help much ini my case .. maybe due to the 315 Toyos ..
     
  5. TrickyT

    TrickyT Hate that mud... SILVER Star

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    Yup, on a A343F control of the transmission is done electronically. Coil #3 in ECT solenoid controls torque converter lockup according to the EWD (see page 135 of the 1997 edition).
     
  6. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    pretty insteresting .. how it can control it . ? ( means electronically )
     
  7. 96r50

    96r50

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    Thanks! What you say is definitely true, it is impossible to tell if the sensor is interconnected with any other aspect of the automatic transmission function without talking to the engineer who designed the ECU. I will edit my original post to reflect that.

    I will be keeping a close eye and ear on the transmission with regards to any difference in operation. I know from reading here and from discussing it with the guys in the Lexus shop that the transmission won't shift into overdrive before coolant temperature reaches a certain point (55C IIRC) in order to get the engine up to operating temperature faster. I haven't found anything with any connection to the ATF temperature in all of my research or discussions (not to say that there isn't some info still out there that I have yet to see). I also place a good deal of faith in the knowledge and info I got from my friend (the Lexus Head technician). He knows that my priorities are aimed at keeping all required OEM systems intact and not compromising anything when adding a modification such as this. I guess what I am saying is that I am quite comfortable with removing the OEM ATF temperature sender to add in a temperature gauge. From what I have learned thus far, it will not affect the operation of the transmission (my opinion only!).

    I will report back if I ever find anything out of the ordinary.
    :cheers:
     
  8. nicholas

    nicholas

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    Nice clean install. Luckily my hose hack job is hidden by the skid plate. I'm glad you posted pictures because I was wondering how accurate my sender location is. But it appears that I am getting the same readings as you. FWIW, the picture I posted in the previous page actually had more nipples than I actually installed. I was able to install the sensor directly into the tee with about 3/8-1/2" of the sensor tip in the flow of ATF. Obviously there could be a slight amount of cooling taking pace as the ATF moves from the trans to the cooler, but the overall trend is what I was most concerned about.

    I agree that this is one of my most useful mods for real time data. It's amazing to see how punching a little boost can drive trans temps up pretty high. It definitely gives you a good warning so you can adjust your driving style accordingly. It seems like having the 315's with stock gears also makes it run a little warmer than with 33's. As long as you have a little speed the cooler does a dang good job. I couldn't imagine driving a truck without a cooler. No wonder so many other cars have problems with transmission failure compared to the 80.
     
  9. 96r50

    96r50

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    A quick update:

    3 months and approximately 10,000 miles later, I'm still loving this gauge. My brother and I spent 6 weeks in June and July driving across Canada in the truck loaded down with all sorts of junk and a couple big DH bikes on a rack out back. It was very reassuring to be able to monitor transmission temperatures while climbing some of the mountain passes in BC and see that the fluid was indeed getting hot on some of the climbs, but not hot enough to warrant pulling over. Near the end of the trip the fluid in my modified blue fan clutch appeared to give up the ghost so we had minimal airflow through the radiator and transmission cooler at low speeds. Between the Scangauge and this gauge it was easy to tell when to pull over and let the truck idle and cool down so we wouldn't burn anything up or blow a headgasket. This gauge is still one of my favourite additions to my truck!

    On a related note, I have not noticed any different behaviour from my engine or transmission while operating without the ATF temperature sender in place. I still agree with TrickyT that we can never know for sure whether the ECU relies on the OEM transmission temperature sender for anything other than turning on the ATF idiot light; however after a couple months and a lot of hard driving (20 hour periods of driving, only stopping for gas) I am comfortable with modifying the system as I have.
     
  10. nitro3421

    nitro3421

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    So I ordered the VDO 323-091 sending unit for the VDO 310-107 gauge. I would like to attach the sending unit to one of the my 3/8" flexible cooler lines (this is for an FJ62 application). I've been searching high and low for the last two hours trying to find a way to get the M10 x 1.5 threads of the sending unit into the 3/8 flexible cooler line with a series of tees and adapters.

    I can't seem to find the right series of metric to NPT to 3/8" barbed tee connections. Has anyone found a set of adapters to get the 323-091 VDO sending unit into a 3/8" flexible cooler line??

    I got into this mess thinking the drain plug on the 80 series was the same as an FJ62. Nope, the FJ62 drain plug is much larger and I can't just put the sending unit into the pan. Anyways, I feel putting the sender in the cooler line will be more accurate anyways.

    I'm also willing to buying a new sending unit for the VDO 310-107 gauge that would be easier to get into the 3/8" flexible line. Would this be a better option?
    http://www.summitracing.com/parts/VDO-323086/

    Also, what type of wire/connectors should be used to connect the sending unit to the gauge? In one of the posts in this thread it looked like their was a premolded rubber piece which went over the end of the nail shaped sending unit head that had two wires coming out of it. Where did this come from?

    Any help would be GREATLY appreciated!
     
    Last edited: May 15, 2010
  11. S.CarolinaFZJ80

    S.CarolinaFZJ80 SILVER Star

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    Reviving an "old" thread to solicite help from those of you who are more knowledgeable about transmissions than I.

    Over the years, I have heeded the advise of others on Mud and ensured my trans was serviced routinely and the fluid level was at the correct level. I have always used Napa Dexron III and drain and refill the pan at every other engine oil change.

    I have the VDO Trans Temp Gauge with the temp sensor located in a "T" fitting like the one Nicholas has pictured in post#46. It is tapped into the transmission outflow line going to the radiator and mounted aft of the front crossmember.

    This setup has worked great & consistently for the last year and a half. I normally get approximately 130-150F highway driving and 190-205F in "heavy" stop and go traffic. It usually takes 20-30 minutes to get the trans temp up to 180F. I recently dropped the pan (1,600 miles ago) to clean the magnets and replace the trans filter. It was the 2nd time doing this in the last 3 years. The fluid was NOT burnt, was pink/red in color and looked new. My previous service and filter change was 17,000 miles prior to this with minimal trace amounts of metal on the magnets. There was the same minimal amounts of metalic residue on the magnets 1,600 miles ago too. So no change in trend of metalic particles of quality of fluid.

    So heres the problem, yesterday, the trans temp went up to 225F RAPIDLY in stop and go traffic. I was not towing anything at the time nor was I driving steep grades. I was just on normal flat surface streets. So after letting the fluid cool down in Park, it operated at 160F on the highway on the way home only to shoot back up to 225F right when I started on city streets again. It appears that the low gears are creating TONS of heat quickly with no change in level of ATF. It is still at the correct level with no evidence of leaks anywhere in the system.

    So what are your thoughts? Have any of you, with temp gauges, experienced this? If so, what was the cause?

    Should I be setting aside some $$$$$ for a Rodneys Transmission at this point or is there still a chane to squeak some life out of my current transmission?

    Thanks in advance for you comments.
     
    Last edited: Aug 26, 2011
  12. Tapage

    Tapage Club 4X4 Panamá SILVER Star

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    Did you have any way to measure if your water temp / oil temp it's also increasing .: ?

    I'm thinking in your rad having just more job to keep on ..
     
  13. S.CarolinaFZJ80

    S.CarolinaFZJ80 SILVER Star

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    Tapage - Definetly worth looking into. To answer your questions, I have a ScanGauge II and it was showing water temp of 190F. I do not have an oil temp gauge but the level and pressure are good. Additionally, the radiator was replaced by the PO 4 or 5 years ago with an FJ80 brass radiator.
     
  14. S.CarolinaFZJ80

    S.CarolinaFZJ80 SILVER Star

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    So any other thoughts on what could cause rapid increases in trans fluid temp in gears 1-3 yet normal temps in overdrive?
     
  15. kbahus

    kbahus

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    Does anyone know at what temp the idiot light will trigger at? Looking for the actual value.
     
  16. S.CarolinaFZJ80

    S.CarolinaFZJ80 SILVER Star

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  17. Douglas S

    Douglas S

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    Ever find out anything more? I have my sender in the outlet union and hit some high temps in stop and go traffic on the way to work this morning. Normally my commute flows pretty quickly, but there was a bit of a jam this morning and the trans temp startled me.

    A442f with FZJ80 cooler.
     
  18. asutherland

    asutherland VA7 HDT

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    Following. Same here.
     
  19. S.CarolinaFZJ80

    S.CarolinaFZJ80 SILVER Star

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    @DouglasS - It hasn't done it since. I am getting 190-200F AT temp in stop-n-go city traffic and 160F Highway consistently in the summer heat of upper 80's F to upper 90's F air temps.
    IIRC, I drained the transmission fluid and refilled it after my high temp issue. Never had a problem since.
    Better go knock on wood now.
     
    Douglas S likes this.
  20. asutherland

    asutherland VA7 HDT

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    Oops, turned out my issue was a faulty gauge/sender. My temp was actually only 135+- .... when it was showing 250 :O
     
    Douglas S likes this.
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