P0712

Schematic:

Circuit Description with 4L30-E Automatic Transmission
The automatic Transmission Fluid Temperature (TFT) sensor is part of the automatic transmission wiring harness assembly. The TFT sensor is a resistor, or thermistor, which changes value based on temperature. The sensor has a negative-temperature coefficient. This means that as the temperature increases, the resistance decreases, and as the temperature decreases, the resistance increases. The Transmission Control Module (TCM) supplies a 5-volt reference signal to the sensor on circuit FP722 and measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance is high and the TCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases.

If the TCM detects an open or a short to ground in the TFT sensor or signal circuit, then DTC P0712 sets. DTC P0712 is a type C DTC.

CONDITION FOR RUNNING THE DTC
The ignition switch is in the RUN position.

CONDITIONS FOR SETTING THE DTC
^ The TFT is less than 98 mV.
^ Condition present for 20 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The TCM flashes the sport mode lamp.
^ The ECM records the operating conditions in the Failure Records at the time of the request from the TCM.
^ The TCM memory stores the DTC at the time of the first failure.
^ The transmission temperature defaults to 130°C (266°F).
^ The TCM will freeze shift adapts.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The TCM stops flashing the sport mode lamp as soon as the fault is no longer present.
^ A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic.
^ The scan tool clears the MIL/DTC.
^ The TCM cancels the DTC default mode actions when the fault no longer exists.

DIAGNOSTIC AIDS
Use the J 35616-A connector test adapter kit for any test that requires probing the TCM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:
^ Poor connections at the TCM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
Refer to General Electrical Diagnosis Procedures in Diagrams for proper procedure.
^ Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving any related connectors and any wiring harnesses. A change in the display may help to locate the fault.

TEST DESCRIPTION

Diagnostic Chart:

The numbers below refer to the step numbers on the Diagnostic Table.
3. This step tests the TCMs ability to detect an open circuit. If the TCM recognizes the open, this eliminates the TCM and the wiring up to the transmission connector from having the fault. The fault must be internal to the transmission.
5. This step inspects for the two TFT circuits for being shorted together.
9. Since the TFT is an integral part of the transmission wiring, the entire harness must be replaced.