I'm not familiar with the six speed, but on the 4 speeds the trans temperature sensor is located in the 'transmission range sensor'. Which is located on top of the valve body which is inside the tranny. I'd check the wiring before you disassemble stuff. The sensor might be good.

 

The ATF temperature sensor is part of the 62TE TRS (transaxle range sensor). It is a thermistor that is not normally serviced separately from the switch.
Usually these don't fail in service and P0713 may be from a wiring or connector terminal problem. It is important to determine this first before faulting the component.
Probe pins # 22 DG/Or and #23 DBu/DG in the solenoid pack/TRS connector with an ohmmeter. A 'high' fault would indicate an open circuit is possible.
Pins #1 and # 23 are grounds and should both have good continuity to each other and to ground.
Pin # 22 should terminate in the PCM connector C4-pin # 35 (follow the DG/Or wire). There has to be good continuity between these 2 points.

Possible Causes:
SENSOR GROUND OPEN
TRANSMISSION TEMPERATURE SIGNAL CIRCUIT OPEN
TRANSMISSION TEMPERATURE SIGNAL CIRCUIT SHORTED TO VOLTAGE
TRANSMISSION TEMPERATURE SENSOR (IN TRS ASSEMBLY)
POWERTRAIN CONTROL MODULE (PCM)

See connector pinout here:
Sonnax 62TE Solenoid Identification & Connector Pin Out (at http://www.sonnax.com/tech_resources/312-62te-solenoid-identification-connector-pin-out )

 

Now I checked it with the Diagnostic Tool (Witech) in the PCM view (Data).
This error is only set when I press the shift lever into the (R) or (D) position. Never at the (P) or (N) Position.
In the (R) Position the error appears sometimes and in the (D) Position almost always.
Probably this is related with the pressure sensor, since he has a common ground line to the temperature sensor connected together in the cable harness (Connection-Point S 129) ?
Is it possible ?

 

Now I finally found this stupid error.
The ground cable (Pin 23) from the Transmission Temperature Sensor was broken, directly at the output from the big Connector to the cable harness at the Transmission Solenoid Pack.
It was'nt easy to disassemble this connector, to remove the crimped pin, and solder on a new cable piece to that pin. But I did it.
Unbelievable that a cable in such a place can break off at all !

 

Glad to hear you found and fixed tt yourself. Nice work, wingman. And I agree with you. I don't see how it could break in that location, but maybe it was cracked at installation and just gradually got worse?