Howdy all,

I'm going to be towing quite a load this summer moving from CA to ID, and through the desert and some high elevation so I wanted to ensure I have an idea of what my trans temp is doing so I don't cook it. I used to have the Snapon MT2500 ("red brick") which did have the trans temp but I have since unfortunately sold it. Does anyone know of a bluetooth or standard OBD2 scanner that can read trans temp? I really don't want to install an aftermarket sensor or any of that as the transmission is currently under warranty and I don't want to do anything that would give the company I bought it from reason to void it.

Thanks!

The OBD2 implementation in these old trucks is the bare minimum and does not have any additional PIDs like the transmission temp. The reason your old MT2500 and other advanced diag tools can read the transmission temp is that they talk to the PCM via the SCI Serial Communications Interface, which is physically different from the OBD2 connection. This interface has many more capabilities all the way to flash programming.
Way back I spent some time with an OBD2 tool that allows to create custom PID queries but could not get anything useful back.

Do you have the trailer package? You could use a "T" fitting on the cooler line to add a sensor.

How do I know if I have the trailer package? The vehicle has a trailer connector/plug towards the rear end that appears stock so I'm guessing yes?

Go here, run your VIN, case-sensitive though, so, all caps please. That'll tell ya what came on your truck from the factory.

According to the site I have the “Trailer Tow Group” so I’m assuming that answer is yes?

Yep, should be an aux trans cooler between the a/c condenser, and the radiator then.

There is indeed! Any chance you know of a good brand of sensor/gauge off the top of your head? Otherwise I’ll just hit up eBay. Thanks for the help! 🙏

Now thinking about it it doesn't matter if you have the trailer package. You can install a fitting on the line going to the radiator(same one with check valve I believe. Can't seem to find a diagram). I think putting a "T" right out of the trans would be the best spot for a accurate reading though.

That's where it was on the pre-96 trucks that actually had a sensor.

I *think* I have seen gauges that will read from the diagnostic port as well, but, I don't recall where......