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Trans. temp gauge stopped working. Found lose wire under coach. IT is hot wire to gauge. If I ground wire to frame the gauge pegs out. My question is where is the sending unit located. 1999 Safari Sahara 3506 3126B (300hp) MD3060.

From what I've been able to see on the Allison site looking at the info they provide on our transmissions, the temperature is a thermistor in the control module and not an actual "sending unit". From their troubleshooting manual: A temperature sensor (thermistor) is located in the internal wiring harness. Changes in sump fluid temperature are indicated by changes in sensor resistance which changes the signal sent to the ECU (see chart in Section 6, Code 24).

Not really much help from their info, but I'd suggest looking at your wiring harness close to where you found the loose wire and see if you can locate the other end of it. Looking at the troubleshooting manual is kind of like going down the rabbit hole - a whole lot of info but no (to me at least) clear guidance on where stuff it at and how to remedy something like you've got.

The transmission temp sensor for the drivers instrument panel is usually on the passenger side of the engine compartment towards the radiator. Either on a transmission cooler line or the transmission cooler section of the rad. Usually it is a threaded stud, as the temperature of the transmission fluid goes up the resistance goes down and your gauge will move up.

The circled sensor is most likely what is on your RV the other ones are possible.

Thank you very much I will look at those parts to check to see if it is there.