Transmission temps... Maestro added, temp is startling

2008 v6 auto Sport with towing package, so it has an oil and transmission cooler. I installed a new head-unit with Maestro data thing. I also replaced all the fluids, including transmission. The readout for my transmission temp has me concerned.

From the research I've done this is pretty high, but there are several places temperature can be taken. The Maestro gets its information from the CAN buss, but not sure where the sensor is. This picture was taken at a stop light - I had been in 5th gear, about 1200 rpm traveling down a city street. Temp outside was 90f.

What do you think?

 

That's really high, have you verified the temp reading is correct by letting it sit overnight and seeing if the temp reading matches ambient temp?

 

No, but I will tomorrow morning. Thanks for the tip.

 

I'm sick to my stomach right now. It just hit me - When I picked it up from the shop today they told me the transmission was overfilled (they replaced a bad gasket on the fill plug). I had changed the fluid last week and thought I'd brought it up to full temp when filling it, but now I bet I didn't. I'd guess between then and now, I've put about a dozen miles on it, all local streets. I'm guessing it's more likely I effed it up than a bad sensor. F me. We're driving to Texas in 2 weeks to bring back a camper trailer.

 

Overfilled by a bit isn't gona hurt anything, even slightly underfilled isn't gona cause damage right away.

The correct check temp is 97-115F, trans in park and engine running.

 

That can't be right, at that temp you'd be on borrowed time and the trans would feel like it was slipping with a bit of flare under WOT or even on part throttle upshifts. I mean at that temp you could spray water on the trans pan and watch it boil off to validate.

 

I'm really hoping the Maestro readings are wrong. I've been researching and found that sometimes they are wrong as a result of faulty wiring or other issues. In the short time I've driven it, it didn't behave abnormally (slipping gears or other issues). I do have a scan tool, so when I check the temp tomorrow morning I'll connect that as well. I haven't used it for trans temp before, but I'm sure I can find that function in its byzantine layout.

Thanks for all the replies- it has helped settle my nerves a bit.

 

Curious about how the Maestro is converting temps? There are custom parameters that need to be entered to convert CAN bus info into readable temperature. Can't remember if they are needed for tranny sump and the torque converter, or just the TC... Do like Dm93 suggested, or if you have an IR gun, shoot the bottom of the pan. It will be accurate to within a few degrees. If the 246F temp is correct, that fluid is all but toast and needs to be changed. Assuming you can read TC temps on your system, I'd definitely use that for your reference. It is a leading indicator for the trans sump temp and can easily be 40F higher than the sump when you start lugging the engine. Driving in 4th gear is your friend when loaded or lugging. Good luck.

 

Oh Happy Days! Thanks @Dm93 - went out this morning and the outside temp was 64 (the low was 54), fired up the truck and checked the Maestro gauges. They read trans temp as 145f. Insert big sigh of relief here!

Thank god there's either a wiring issue or a bad sensor, rather than a transmission fubar. I couldn't find my scanning tool at the time (house is chaos as we get all the things together for the trip), but found it a short while ago. I'll repeat the test tomorrow morning and see what the scan tool says. If it shows close to ambient, then I know Maestro is the issue.

I'll watch the scanning readout and the Maestro, see what they say once it's warmed up, and know whatever Maestro shows (i.e. 240f) is actually the normal temp. That will have to do until we get back and can figure out the issue.

Thanks everyone for suggestions and comments.

 

I've seen that mentioned many times - drive in 4th when towing - and will definitely do so.

 

I'd bet it's a calculation/programming issue with your head unit rather than an issue with the truck as @MR5X5 says, you would have an A/T Temp warning light on if the truck was seeing that high of temp.

 

I'll reset the PIDs and see if that does it. If not, reach out to Maestro and see what they say.

I'm kind of disappointed in what gauges they have/don't have. Intake temp, load, etc don't really care. I'd like to see oil temp and pressure and coolant temp. The fuel% is blank becuase, apparently, Toyota doesn't have that data in the CAN bus.

 

Coolant temp should be there but there are no oil pressure or temp sensors and the fuel level sensor isn't tied to the ECM so fuel level isn't reported either.

 

To me the below are normal operating temps: Your temps seem kind of high.
My operating engine coolant between 185-2005 F*
Look at the screen print for Torque Con and Pan temp, About 160F driving 65 MPH freeway flat.
Thermostat PINNED open

Good advice to let it sit overnight and take temps again as a BASELINE.

I don't know about Maestro. I use Torque Pro app on my tablet with a Tanglog ODB 2 car code reader

At 106F* on the freeway the temps were about 8F higher in the Pan and the Con.
Live in SE Arizona desert - heat out the waazoo - 110F yesterday

See posts at https://www.tacomaworld.com/threads/3rd-gen-transmission-cooler-upgrade.482280/page-23.
My post is at #451