Inspection Procedure 5: Slip at backward driving


COMMENTS ON TROUBLE SYMPTOM



PROBABLE CAUSES



  • Malfunction of input shaft speed sensor system
  • Malfunction of torque converter
  • Malfunction of valve body (line pressure control solenoid)
  • Malfunction of the A/T-ECU
  • A/T internal error (oil pump, clutch C3, brake B1/B4, one-way clutch F1, etc.)

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list
Item 5: Input shaft speed sensor (Refer to data list reference table ).

Q. Is the check result normal?
Go to Step 2.
Repair the input shaft speed sensor system.

STEP 2. Hydraulic pressure test
Measure the line pressure (Refer to ).
note If a slip occurs during backward driving, the line pressure may be lower than the standard value.
OK: Refer to .

Q. Is the check result normal?
Go to Step 3.
Go to Step 4.

STEP 3. Retest the system
If the trouble symptom is not solved, replace the torque converter. Then, check the trouble symptom again.

Q. Is the trouble symptom reproduced?
Go to Step 5.
This diagnosis is complete.

STEP 4. Retest the system
If the trouble symptom is not solved, replace the valve body. Then, check the trouble symptom again.

Q. Is the trouble symptom reproduced?
Go to Step 5.
This diagnosis is complete.

STEP 5. A/T-ECU replacement
(1)Replace the A/T-ECU.
(2)Test drive the vehicle.
(3)Verify that the condition described by the customer exists.

Q. Is the trouble symptom reproduced?
After checking the oil pump for damage, check each clutch and brake for any damage, and replace if necessary. (It is highly possible that the clutch C3, brake B1/B4, and one-way clutch F1 that engage in reverse gear are damaged.)
This diagnosis is complete.