P0713

P0713 is the mirror of P0712: the TCM sees the TFT signal pinned at or near reference voltage (typically above 4.85V for 5+ seconds), which corresponds to either an open circuit (sensor disconnected, broken wire, or open thermistor element) or a fluid temperature below the sensor's valid range (below roughly -40F). The substitute value the TCM uses when this code is active is usually -40F, which forces the trans into a cold-fluid strategy with delayed shifts and torque-converter unlock disabled, so the customer complaint is almost always harsh or delayed shifts plus a CEL. Cheap diagnostics: at the case connector with key-on, jumper the signal pin to ground through a known resistor (1,000 ohms simulates roughly 200F), if the live data jumps to the corresponding temp the TCM and wiring are healthy and the sensor or its internal connection is open; if the reading does not respond the fault is in the harness between the case and the TCM or inside the TCM itself. Ohm the signal wire end-to-end with the case connector disconnected and the TCM connector disconnected, expect under 5 ohms for a continuous wire. Expensive misdiagnosis: do not condemn the TCM for a no-response-to-jumper test until you have verified TCM power and ground, a corroded TCM ground (commonly on a body or trans-case bolt) produces identical symptoms and is a 15-minute fix.

Vehicle-specific patterns: 2005-2010 Ford Mustang/F-150 with 5R55S/6R80 sees P0713 from the external case-connector pin backing out under vibration, a $40 pigtail repair; 2007-2013 Mercedes 7G-Tronic (722.9) throws P0713 when the 13-pin connector adapter at the valve body leaks ATF up the wires and oxidizes the TCM pins, the 13-pin adapter is a $90-150 part and a published Mercedes WIS procedure; 2008-2014 Subaru Outback/Legacy with 4EAT/5EAT has a discrete external TFT sensor that fails as a unit and is individually serviceable. Estimated repair: $100 to $2,100.