P0840

DTC P0840: Malfunction of Secondary Pressure Sensor














DIAGNOSTIC FUNCTION
TCM conducts fault detection by monitoring the output voltage of the secondary pressure sensor.

DESCRIPTIONS OF MONITOR METHODS
^ The status with the fluid temperature of -20°C (-4°F) or more and with the secondary pressure sensor voltage of 4.69 V or more continues for 5 seconds.
^ The status with the fluid temperature of -20°C (-4°F) or more and with the secondary pressure sensor voltage of 0.09 V or less continues for 5 seconds.

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)
^ P0746: Abnormality in hydraulic control system function
^ P0841: Abnormality in line pressure sensor function
^ P0868: Secondary pressure drop

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

LOGIC FLOW CHARTS (Monitor Sequence)

Logic Flow Charts (Monitor Sequence):

DTC SET CONDITIONS

Judgement Criteria
^ Secondary pressure sensor voltage [transmission fluid temperature: more than -20°C (-4°F)]: 4.69 volts or more. (5 seconds)
^ Secondary pressure sensor voltage [transmission fluid temperature: more than -20°C (-4°F)]: 0.09 volt or less. (5 seconds)

OBD-II DRIVE CYCLE PATTERN
All the conditions below continue for 6 seconds.
^ Transmission range switch: D
^ Vehicle speed: 10 km/h (6.2 mph) or more
^ Throttle position: 1/8 or more
^ Engine speed: 450 r/min or more
^ Transmission fluid temperature: 20°C (68°F) or more.
^ Transmission fluid temperature: 99°C (210°F) or more.

PROBABLE CAUSES
^ Malfunction of valve body assembly (Faulty secondary pressure sensor)
^ Damaged wiring harness and connectors
^ Malfunction of TCM

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III data list
^ Item 4: Secondary pressure sensor signal (Refer to Data List Reference Table.) Data List Reference Table

Q: Is the check result normal?
YES: Intermittent malfunction
NO: Go to Step 2.

STEP 2. Check the following connector:
^ B-08 CVT assembly connector
^ C-40 TCM connector
^ A-09 Intermediate connector

Check the terminals for a contact status problem and internal short circuit.

Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the defective connector.

STEP 3. Check for open circuit and short to ground in the wiring harness between the TCM connector and the CVT assembly connector.
^ Between C-40 TCM connector (terminal No.39) and B-08 CVT assembly connector (terminal No.7)
^ Between C-40 TCM connector (terminal No.48) and B-08 CVT assembly connector (terminal No.19)
^ Between C-40 TCM connector (terminal No.49) and B-08 CVT assembly connector (terminal No.5)

Q: Is the check result normal?
YES: Go to Step 4.
NO: Repair the wiring harness.

STEP 4. Symptom recheck after replacing the valve body assembly

Q: Is the check result normal?
YES: The inspection is complete.
NO: Replace TCM.