P0712

DTC P0712 Transaxle Fluid Temperature Sensor Diagnostic Chart:

Transaxle Fluid Temperature Sensor Wiring Schematic:

CIRCUIT DESCRIPTION
The Transaxle Fluid Temperature (TFT) sensor uses a thermistor to vary the signal voltage to the Powertrain Control Module (PCM) according to temperature. The PCM applies a voltage on CKT 1227 to the sensor. When the transaxle is cold the sensor resistance is high, therefore, the PCM will monitor a high signal voltage. As the transaxle warms, the sensor resistance becomes less and the voltage drops. At normal operating temperature 20°C to 90°C (68°F to 194°F) the trans temp signal will measure about 2-4 volts.


DIAGNOSTIC TROUBLE CODE (DTC) PO712 WILL SET WHEN
^ Engine run time is over 2 minutes.
^ Transaxle fluid temperature sensor signal indicates a temperature below -36°C (-33°F).
^ Above conditions for over 1 second.


ACTION TAKEN (PCM WILL DEFAULT TO)
With a current DTC PO712 set, the PCM will substitute the Engine Coolant Temperature (ECT) sensor value for transaxle fluid temperature. DTC PO712 does not illuminate the Malfunction Indicator Lamp (MIL).

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Determines if conditions necessary to set DTC PO712 exist.
2. Simulates conditions to set DTC P0713. If the PCM recognizes the low signal voltage and sets DTC PO713, the wiring and PCM are OK.
3. This test will determine if CKT 1227 is open. There should be 5 volts present at the sensor connector if measured with a digital voltmeter.


DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.

Check for:
^ Poor connection or damaged harness - Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
^ Intermittent test - Monitor a Tech 1 scan tool while moving related connectors and wiring harness. If the failure is induced, the scan data will change from low to high or high to low. This may help to isolate the location of the malfunction.