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P0712

DTC P1764 (P0712): Transmission Fluid Temperature Sensor System (Short Circuit)








CIRCUIT OPERATION
^ The PCM, (terminal 74) applies 5 volts to the transmission fluid temperature sensor output terminal (terminal 1).
^ The transmission fluid temperature sensor circuit is grounded to the PCM, (terminal 69).
^ When the transmission fluid temperature is cold, the transmission fluid temperature sensor resistance is high. When the transmission fluid temperature is hot, the transmission fluid temperature sensor resistance is low.

DESCRIPTIONS OF MONITOR METHODS
^ If transmission fluid temperature equals or exceeds specified value, PCM, judges that transmission fluid temperature sensor has a failure.

MONITOR EXECUTION
^ Continuous

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
^ Not applicable

Sensor (The sensor below is determined to be normal)
^ Not applicable

LOGIC FLOW CHARTS (Monitor Sequence):





DTC SET CONDITIONS

Check Conditions, Judgement Criteria
^ Transmission fluid temperature sensor voltage: 0.2 volt or less. (1 second)

OBD-II DRIVE CYCLE PATTERN
Start the engine, keep the vehicle stopped in "P" range for 5 seconds.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
^ Malfunction of the transmission fluid temperature sensor circuit
^ Damaged harness or connector
^ Malfunction of the PCM

DIAGNOSIS

Required Special Tool:
^ MB991958: Scan Tool (M.U.T-III Sub Assembly)
^ MB991824: V.C.I.
^ MB991827: M.U.T-III USB Cable
^ MB991910: M.U.T-III Main Harness A

STEP 1. Using scan tool MB991958, check data list item 7: Transmission Fluid Temperature Sensor.

CAUTION





To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1) Connect scan tool MB991958 to the data link connector.
2) Start the engine.
3) Set scan tool MB991958 to the data reading mode.
^ Item 7: Transmission Fluid Temperature Sensor.
^ When the engine is cool: Almost equal to the ambient temperature (atmospheric temperature)

NOTE: Set scan tool MB991958 to the data reading mode for item number 5, Intake Air Temperature (IAT) Sensor and note the temperature measurement. When the engine is cool, the temperature should be almost equal to the ambient temperature (atmospheric temperature), and the IAT sensor measurement should be approximately the same as the Transmission Fluid Temperature Sensor.

^ When the engine is warm: 70 - 80°C (158 - 176°F)
4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: It can be assumed that this malfunction is intermittent.

NO: Go to Step 2.

STEP 2. Measure the sensor output voltage at the A/T control solenoid valve assembly connector B-108 by backprobing.





1) Do not disconnect connector B-108.
2) Turn the ignition switch to the "ON" position.





3) Measure the voltage between terminal 1 and ground by backprobing.
^ When transmission fluid temperature is 20°C (68°F), voltage should measure between 3.8 and 4.0 volts.
^ When transmission fluid temperature is 40°C (104°F), voltage should measure between 3.2 and 3.4 volts.
^ When transmission fluid temperature is 80°C (176°F) voltage should measure between 1.7 and 1.9 volts.
4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage within the specified range?
YES: Go to Step 6.
NO: Go to Step 3.

STEP 3. Check A/T control solenoid valve assembly connector B-108 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 4.
NO: Repair or replace the damaged components.

STEP 4. Check the sensor output voltage at A/T control solenoid valve assembly connector B-108.





1) Disconnect connector B-108 and measure at the harness side.
2) Turn the ignition switch to the "ON" position.





3) Measure the voltage between terminal 1 and ground.
^ The voltage should measure between 4.5 and 4.9 volts.
4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?
YES: Go to Step 5.
NO: Go to Step 7.

STEP 5. Check the transmission fluid temperature sensor at A/T control solenoid valve assembly connector B-108.





1) Disconnect connector B-108 and measure at the sensor side.





2) Measure the resistance between terminal 1 and 2.
^ When transmission fluid temperature is 0°C (32°F), resistance should be between 16.7 and 20.5 kOhms.
^ When transmission fluid temperature is 20°C (68°F), resistance should be between 7.3 and 8.9 kOhms.
^ When transmission fluid temperature is 40°C (104°F), resistance should be between 3.4 and 4.2 kOhms.
^ When transmission fluid temperature is 60°C (140°F), resistance should be between 1.9 and 2.2 kOhms.
^ When transmission fluid temperature is 80°C 176°F) resistance should be between 1.0 and 1.2 kOhms.
^ When transmission fluid temperature is 100°C (212°F) resistance should be between 0.57 and 0.69 kOhms.
Q: Is the measured resistance within the specified range?
YES: Go to Step 6.
NO: Replace the transmission fluid temperature sensor.

STEP 6. Using scan tool MB991958, check data list item 7: Transmission Fluid Temperature Sensor.

CAUTION





To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1) Connect scan tool MB991958 to the data link connector.
2) Start the engine.
3) Set scan tool MB991958 to the data reading mode.
^ Item 7: Transmission Fluid Temperature Sensor.
^ When the engine is cool: Almost equal to the ambient temperature (atmospheric temperature)

NOTE: Set scan tool MB991958 to the data reading mode for item number 13, Intake Air Temperature (IAT) Sensor and note the temperature measurement. When the engine is cool, the temperature should be almost equal to the ambient temperature (atmospheric temperature), and the IAT sensor measurement should be approximately the same as the Transmission Fluid Temperature Sensor

^ When the engine is warm: 70 - 80°C (158 - 176°F)
4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: It can be assumed that this malfunction is intermittent.
NO: Replace the PCM. When the PCM is replaced, register the encrypted code.

STEP 7. Measure the sensor output voltage at PCM connector B21 by using check harness special tool MB991923.





1) Disconnect all the connectors from the PCM,





2) Connect special tool MB991923 (check harness) between the PCM, and the body-side harness connector.
3) Turn the ignition switch to the "ON" position.





4) Measure the voltage between terminal 74 and ground.
^ When transmission fluid temperature is 20°C (68°F), voltage should measure between 3.8 and 4.0 volts.
^ When transmission fluid temperature is 40°C (104°F), voltage should measure between 3.2 and 3.4 volts.
^ When transmission fluid temperature is 80°C (176°F), voltage should measure between 1.7 and 1.9 volts.
5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage within the specified range?
YES: Go to Step 6.
NO: Go to Step 8.

STEP 8. Check PCM, connector B-21 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 9.
NO: Repair or replace the damaged components.

STEP 9. Check the harness for a short circuit to ground between PCM, connector B-21 terminal 74 and A/T control solenoid valve connector B-108 terminal 1.





Q: Is the harness wire in good condition?
YES: Go to Step 6.
NO: Repair or replace the harness wire.





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