DTC P0712 Transmission Fluid
Temperature (TFT) Sensor Circuit Low Input 5.7L
The automatic
transmission fluid temperature (TFT) sensor is part of the automatic
transmission fluid pressure (TFP) manual valve position switch. 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 powertrain
control module (PCM) supplies a 5-volt reference signal to the sensor on
circuit 1227 and measures the voltage drop in the circuit. When the
transmission fluid is cold, the sensor resistance is high and the PCM detects
high signal voltage. As the fluid temperature warms to a normal operating temperature,
the resistance becomes less and the signal voltage decreases. The PCM uses this
information to control shift quality and torque converter clutch apply.
When the PCM detects a
continuous short to ground in the TFT signal circuit or in the TFT sensor, then
DTC P0712 sets. DTC P0712 is a type C DTC.
Conditions
for Running the DTC
- The system voltage is
8-18 volts.
- The ignition is ON.
Conditions
for Setting the DTC
The TFT sensor indicates
a signal voltage less than 0.2 volts for 10 seconds.
Action
Taken When the DTC Sets
- The PCM does not illuminate the
malfunction indicator lamp (MIL).
- Important
The
actions listed below are in order of highest to lowest priority.
The
PCM determines a default TFT using one of the following:
- If any ECT DTCs P0117 or P0118 are
set, then the default TFT is equal to 135°C (275°F).
- If the ECT is 125°C (257°F) or
more, then the default TFT is equal to 135°C (275°F).
- If the engine run time is less than
300 seconds and:
- No intake air temperature (IAT)
DTCs P0112 or P0113 are set and IAT is available, then the default TFT
is equal to IAT.
- Any IAT DTCs P0112 or P0113 are
set or IAT is NOT available, then the default TFT is equal to 90°C
(194°F).
- If the engine run time is greater
than 300 seconds and no IAT DTCs P0112 or P0113 are set and IAT is
available and ECT is between 40 and 125°C (104 and 257°F) and:
- IAT at startup is less than 15°C
(59°F), then the default TFT is equal to the
ECT plus 5°C (8°F).
- IAT at startup is greater than
35°C (95°F), then the default TFT is equal to
the ECT plus 10°C (16°F).
- IAT at startup is between 15 and
35°C (59 and 95°F), then the default TFT is equal to the ECT.
- If the engine run time is greater
than 300 seconds and any IAT DTCs P0112 or P0113 are set or IAT is
NOT available, then the default TFT is equal to the ECT.
- If the engine run time is greater
than 300 seconds and ECT is less than 40°C (104°F) or more, then the
default TFT is equal to 60°C (140°F).
- The PCM freezes shift adapts from
being updated.
- The PCM records the operating
conditions when the Conditions for Setting the DTC are met. The PCM stores
this information as Failure Records.
- The PCM stores DTC P0712 in PCM
history.
Conditions
for Clearing the DTC
- A scan tool can clear the DTC.
- The PCM clears the DTC from PCM
history if the vehicle completes 40 warm-up cycles without a
non-emission-related diagnostic fault occurring.
- The PCM cancels the DTC default
actions when the fault no longer exists and/or the ignition switch is OFF
long enough in order to power down the PCM.
- Inspect the connectors at the PCM,
the TFT sensor and all other circuit connecting points for an intermittent
condition. Refer to Testing
for Intermittent and Poor Connections in Wiring Systems.
- Inspect the circuit wiring for an
intermittent condition. Refer to Testing
for Electrical Intermittents in Wiring
Systems.
- The scan tool displays the
transmission fluid temperature in degrees. After the transmission is
operating, the fluid temperature should rise steadily to a normal
operating temperature, then stabilize.
- Verify the customer's driving
habits, trailer towing, etc. Trailer towing should occur in D3.
The numbers below refer
to the step numbers on the diagnostic table.
|
DTC P0712 TFT Sensor Circuit Low Input (5.7L) Step |
Action |
Value(s) |
Yes |
No |
|
Did
you perform the Powertrain Diagnostic System Check?
|
-- |
Go to A
Powertrain On Board Diagnostic (OBD) System Check
in Engine Controls |
||
|
Inspect
for correct transmission fluid level. Refer to Transmission
Fluid Checking Procedure . Did you perform the fluid checking procedure? |
-- |
|||
Important Before
clearing the DTC, use the Scan Tool in
order to record the Failure Records. Using the Clear Info function erases the
Failure Records from the PCM.
Does
the Scan Tool
display a TFT Sensor signal voltage greater than the specified value? |
0.2 V |
Go to Diagnostic Aids |
||
Does
the Scan Tool
display a TFT Sensor signal voltage greater than the specified value? |
4.92 V |
|||
Does
the resistance measure within the specified range? |
3088-3942 ohms at
20°C (68°F) 159-198 ohms at 100°C (212°F) |
Go to Diagnostic Aids |
||
|
Test
the signal circuit (CKT 1227) of the TFT sensor for a short to ground
between the AT inline 20-way connector and the TFT sensor. Refer to Circuit
Testing in Wiring Systems. Did you find a short to ground condition? |
-- |
|||
|
Test
the signal circuit (CKT 1227) of the TFT sensor for a short to ground
between the PCM connector C2 and the AT inline 20-way connector. Refer to Circuit
Testing and Wiring
Repairs in Wiring Systems. Did you find and correct the condition? |
-- |
|||
|
Replace
the TFT sensor (this sensor is part of the TFP manual valve position switch).
Refer to Valve
Body and Pressure Switch Replacement . Did you complete the replacement? |
-- |
-- |
||
|
Replace
the AT wiring harness assembly. Refer to Torque
Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid, TCC Solenoid, and
Wiring Harness . Did you complete the replacement? |
-- |
-- |
||
|
Replace
the PCM. Refer to PCM
Replacement/Programming in Engine Controls. Did you complete the
replacement? |
-- |
-- |
||
|
Perform
the following procedure in order to verify the repair:
Has
the test run and passed? |
-- |
System OK |