DTC P0720: Malfunction of Secondary Pulley Speed Sensor

DIAGNOSTIC FUNCTION

TCM determines that the malfunction is present when the secondary pulley speed sensor value changes abruptly or when there is a discrepancy between this sensor and other sensors in sensor reading.

DESCRIPTIONS OF MONITOR METHODS

The status with the primary pulley speed of 1,000 r/min or more and with the secondary pulley speed of 150 r/min or less continues for 5 seconds.
When the vehicle speed computed by CVT has dropped abruptly from 10 km/h (6.2 mph) or more to 5 km/h (3.1 mph) or less, and then the computing value keeps 5 km/h (3.1 mph) or less for 0.5 seconds continuously.

MONITOR EXECUTION

transmission range:D
Throttle valve opening : 1/8 or more

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)

P0705: Malfunction of transmission range switch
P0712, P0713: Malfunction of the transmission fluid temperature sensor
P0715: Malfunction of primary pulley speed sensor
P0725: Malfunction of engine speed
P0741: Abnormality in lockup function
P0746: Abnormality in hydraulic control system function
P0841: Abnormality in line pressure sensor function
P0868: Secondary pressure drop
P1706: Malfunction of throttle signal
P1723: Abnormality in speed sensor system function

Sensor (The sensor below is determined to be normal)

Transmission range switch
Transmission fluid temperature sensor
Primary pulley speed sensor
Accelerator pedal position sensor

LOGIC FLOW CHARTS (Monitor Sequence)

DTC SET CONDITIONS

Check Conditions

Transmission range switch position: D.
Throttle position sensor voltage: 1.37 volts or more.
Primary pulley speed: 1,000 r/min or more.
Secondary pulley speed at 10 millisecond before: 500 r/min or more.
Voltage of battery: 9 volts or more.
Voltage of battery: 16 volts or less.

Judgment Criteria

Secondary pulley speed [primary pulley speed: 1,000 r/min or more]: 150 r/min or less. (5 seconds)
Secondary pulley speed [secondary speed at 10 millisecond before: 500 r/min or more]: 260 r/min or less. (0.5 second)

OBD-II DRIVE CYCLE PATTERN

transmission range: D (Drive the vehicle for 10 seconds or more while the accelerator opening angle is 20% or more)

PROBABLE CAUSES

Malfunction of secondary pulley speed sensor
Damaged wiring harness and connectors
Malfunction of TCM

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III data list

Item 2: Secondary speed sensor signal (Refer to Data List Reference Table

Q. Is the check result normal?

	Intermittent malfunction

	Go to Step 2.

STEP 2. Check the following connector:

C-40 TCM connector
B-113 Secondary pulley speed sensor connector
A-10 Intermediate connector

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

Q. Is the check result normal?

	Go to Step 3.

	Repair the defective connector.

STEP 3. Check for open circuit in the wiring harness between the secondary pulley speed sensor connector and the TCM connector.

Between B-113 secondary pulley speed sensor connector (terminal No.3) and C-40 TCM connector (terminal No.48)

Q. Is the check result normal?

	Go to Step 4.

	Repair the wiring harness.

STEP 4. Check for open circuit and short to ground in the wiring harness between the secondary pulley speed sensor connector and the TCM connector

Between B-113 secondary pulley speed sensor connector (terminal No.2) and C-40 TCM connector (terminal No.36)

Q. Is the check result normal?

	Go to Step 5.

	Repair the wiring harness.

STEP 5. Check for open circuit in the wiring harness between the CVT control relay and the secondary pulley speed sensor connector.

Between A-15X CVT control relay (terminal No.3) and B-113 secondary pulley speed sensor connector (terminal No.1)

Q. Is the check result normal?

	Go to Step 6.

	Repair the wiring harness.

STEP 6. Secondary pulley speed sensor check

Visually check the tip of the sensor for foreign materials or damage.

Q. Is the check result normal?

	Go to Step 7.

	Repair.

STEP 7. Diagnosis code recheck after replacing the secondary pulley speed sensor

Q. Is the check result normal?

	The procedure is complete.

	Replace TCM.