[ Model - ECLIPSE CROSS / Year - 2018 ]
2018 / ECLIPSE CROSS / EC - Workshop Manual
23 -AUTOMATIC TRANSMISSION > 23A-CVT > TROUBLESHOOTING<CVT><CVT> > DIAGNOSIS CODE PROCEDURES > CODE NO. P0720 SECONDARY PULLEY SPEED SENSOR MALFUNCTION
Code No. P0720: Malfunction of Secondary Pulley Speed Sensor
 
 
 
 
DIAGNOSTIC FUNCTION
The CVT-ECU determines whether the system is defective by monitoring the secondary pulley speed sensor.
 
 
JUDGEMENT CRITERIA
  • 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.
  • 0.5 seconds after the secondary pulley speed has dropped abruptly from 1,000 r/min or more to 215 r/min or less.
  • The pulley ratio is out of specifications when the engine speed, the primary pulley speed and the turbine speed are normal.
 
 
PROBABLE CAUSES
  • Malfunction of secondary pulley speed sensor
  • Damaged wiring harness and connectors
  • Malfunction of CVT-ECU
 
 
DIAGNOSIS PROCEDURE
STEP 1. Check for open circuit in earth line between the secondary pulley speed sensor connector (terminal No. 3) and the body earth
Is the check result normal?
Go to Step 2.
Repair the connector(s) or the wiring harness.
 
STEP 2. Voltage measurement at secondary pulley speed sensor connector (terminal No. 1)
(1) Disconnect the secondary pulley speed sensor connector, and measure at the wiring harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between the secondary pulley speed sensor connector (terminal No. 1) and body earth.
OK: 10 V or more
Is the check result normal?
Go to Step 3.
NO : Repair the connector(s) or the wiring harness (power supply line between the secondary pulley speed sensor connector terminal No. 1 and the CVT control relay connector).
 
STEP 3. Check for open circuit or short to earth in SECS line between the secondary pulley speed sensor connector and the CVT-ECU connector
Is the check result normal?
Go to Step 4.
Repair the connector(s) or the wiring harness.
 
STEP 4. Measure the output wave pattern of the secondary pulley speed sensor at CVT-ECU connector (SECS terminal).
(1) Connect the secondary pulley speed sensor connector and CVT-ECU connector.
(2) Selector lever position: Sport mode (1st gear).
(3) Drive at a constant speed of approx. 20 km/h.
(4) Connect an oscilloscope, and measure the voltage between CVT-ECU connector SECS terminal and body earth.
OK: A wave pattern such as the one shown on (Check Procedure Using an Oscilloscope) should be output. There should be no noise in the output wave pattern.
Is the check result normal?
Go to Step 5.
Visually check the tip of the secondary pulley speed sensor for deposits or damage, and repair or replace it if necessary.
 
STEP 5. Symptom recheck after erasing diagnosis code
Is the diagnosis code set?
Replace the CVT-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).