Code No.P1766 (P0715) Input
shaft speed sensor system
OPERATION
The input shaft speed sensor detects the speed of the underdrive clutch retainer, and
sends the information to the A/T-ECU as a pulse signal.
DIAGNOSIS CODE SET CONDITIONS
The diagnosis code No.P1766 (P0715) is set if the input shaft speed sensor does not send
a pulse signal for one second or more while the 3rd gears are engaged and the vehicle speed
is 40 km/h or more (the output shaft speed sensor speed is 1,000 r/min or
more). If the code No.P1766 (P0715) is set four times, the transmission will be fixed in 3rd
gear as a fail-safe measure. However, the transmission can be downshifted to 2nd gear by operating
the selector lever.
PROBABLE CAUSES
Malfunction of input shaft speed sensor
Malfunction of underdrive clutch retainer
Damaged harness wires and connectors
Malfunction of the A/T-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III data list
Item 05: Input shaft speed sensor (Refer to data list reference table ).
Q.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 -
How to Cope with Intermittent
Malfunction ).
STEP 8. Check the harness between input shaft speed sensor connector
B-17 terminal No.1 and A/T-ECU connector C-12 terminal No.43.
Check the earth line for open circuit.
Q.
Is the check result normal?
Go to Step 6.
Repair the wiring harness.
STEP 9. Measure the voltage at input shaft speed sensor connector
B-17.
(1)Disconnect the connector, and measure the voltage between terminal 3 and earth at the
wiring harness side. (2)Turn the ignition switch to the ON position. OK: System voltage
STEP 11. Check the harness between input shaft speed sensor connector
B-17 terminal No.3 and junction block connector C-208 terminal No.2.
Check the power supply line for short or open circuit.
Q.
Is the check result normal?
Go to Step 6.
Repair the wiring harness.
STEP 12. Measure the voltage at input shaft speed sensor connector
B-17.
(1)Disconnect the connector, and measure the voltage between terminal 2 and earth at the
wiring harness side. (2)Turn the ignition switch to the ON position. OK: 4.5 -
4.9 V
Q.
Is the check result normal?
Go to Step 18.
Go to Step 13.
STEP 13. Measure the voltage at A/T-ECU connector C-12.
STEP 17. Check the harness between input shaft speed sensor connector
B-17 terminal No.2 and A/T-ECU connector C-12 terminal No.31.
Check the output line for open circuit.
Q.
Is the check result normal?
Go to Step 6.
Repair the wiring harness.
STEP 18. Measure the output wave pattern of the input shaft speed
sensor at A/T-ECU connector C-12 (using an oscilloscope).
(1)Shift the selector lever to the D range.
(2)Accelerate the vehicle to approximately 50 km/h (shift range;
3rd).
(3)Connect an oscilloscope, and measure the voltage between A/T-ECU connector C-12
terminal No.31 and earth. OK: A wave pattern such as the one shown on (Check
Procedure Using an Oscilloscope) should be output, and the maximum value should be 4.8 V or
more and the minimum value should be 0.8 V or less. There should be no noise in the output wave
pattern.
Q.
Is the check result normal?
Go to Step 6.
Go to Step 19.
STEP 19. Connector check: C-12 A/T-ECU connector
Check for the contact with terminals.
Q.
Is the check result normal?
Go to Step 20.
Repair the defective connector.
STEP 20. Replace the input shaft speed sensor and then recheck the
diagnosis code.
(1)Replace the input shaft speed sensor.
(2)Test drive the vehicle.
(3)Check if the diagnosis code is set.
Q.
Is diagnosis code P1766 set?
Go to Step 21.
The inspection is complete.
STEP 21. Underdrive clutch retainer inspection
Visually check the underdrive clutch retainer for damage.