Code No.P1779, P1780, P1781, P1782, P1784: Gear Incorrect Ratio
OPERATION
The A/T-ECU detects the current gear/speed according to the output signals from the input and output shaft speed sensor.
DIAGNOSIS CODE SET CONDITIONS
If the output from the output shaft speed sensor multiplied by the gear ratio is not the same as the output from the input shaft speed sensor after completing of shifting, the corresponding diagnosis code is set.
If each diagnosis code is set 4 times, the transmission is fixed in 3rd as a fail-safe measure.
PROBABLE CAUSES
- Malfunction of input shaft speed sensor
- Malfunction of output shaft speed sensor
- Damaged harness wires and connectors
- Malfunction of the A/T-ECU
- Malfunction of solenoid valve
- Malfunction of underdrive clutch retainer
- Malfunction of valve body
- Malfunction of transfer drive gear or driven gear
- Malfunction of low-reverse brake system (for diagnosis codes P1779, P1784)
- Malfunction of underdrive clutch system (for diagnosis codes P1779, P1780, P1781)
- Malfunction of second brake system (for diagnosis codes P1780, P1782)
- Malfunction of overdrive clutch system (for diagnosis codes P1781, P1782)
- Malfunction of reverse clutch system (for diagnosis code P1784)
- Malfunction of one-way clutch system (for diagnosis code P1779)
|
|
STEP 1. M.U.T.-III diagnosis code
|
|
|
Either of diagnosis codes P1779, P1780, P1781, P1782 or P1784 is set, the input shaft speed sensor or output shaft speed sensor is defective.
|
|
|
Q.
Are diagnosis codes P1766 or P1767 set?
|
|
|
YES <diagnosis code P1766 is set> : Refer to diagnosis code P1766 input shaft speed sensor system  .
|
|
|
|
|
|
YES <diagnosis code P1767 is set> : Refer to diagnosis code P1767 output shaft speed sensor system .
|
|
|
|
|
|
 Go to Step 2.
|
|
|
|
|
|
STEP 2. M.U.T.-III diagnosis code
|
|
|
Either of diagnosis codes P1779, P1780, P1781, P1782 or P1784 is set, the corresponding solenoid valve is defective.
|
|
|
Q.
Is either of diagnosis code P1773, P1774, P1775, P1776 set?
|
|
|
YES <diagnosis code P1773 is set> : Refer to diagnosis code P1773: LR solenoid valve system .
|
|
|
|
|
|
YES <diagnosis code P1774 is set> : Refer to diagnosis code P1774: UD solenoid valve system .
|
|
|
|
|
|
YES <diagnosis code P1775 is set> : Refer to diagnosis code P1775: 2ND solenoid valve system .
|
|
|
|
|
|
YES <diagnosis code P1776 is set> : Refer to diagnosis code P1776: OD solenoid valve system .
|
|
|
|
|
|
Go to Step 3.
|
|
|
|
|
|
STEP 3. Hydraulic pressure test
|
|
|
Each hydraulic pressure of the elements below, which diagnosis codes indicate, should be within the standard value.
|
|
|
- diagnosis code P1779: Underdrive clutch, low-reverse brake
- diagnosis code P1780: Underdrive clutch, second brake
- diagnosis code P1781: Underdrive clutch, overdrive clutch
- diagnosis code P1782: Overdrive clutch, second brake
- diagnosis code P1784: Reverse clutch, low-reverse brake
|
|
|
OK: Refer to .
|
|
|
Q.
Is the check result normal?
|
|
|
 Go to Step 6.
|
|
|
|
|
|
NO <some hydraulic pressures are abnormal> : Go to Step 5.
|
|
|
|
|
|
NO <all hydraulic pressure are abnormal> : Go to Step 4.
|
|
|
|
|
|
STEP 4. Adjust the line pressure and recheck the diagnosis code.
|
|
|
(1)Adjust the line pressure (Refer to ).
|
|
|
(2)Test drive the vehicle.
|
|
|
(3)Check the diagnosis code.
|
|
|
Q.
Is the diagnosis code set?
|
|
|
Go to Step 5.
|
|
|
|
|
|
The inspection is complete.
|
|
|
|
|
|
STEP 5. Disassemble, clean and assemble the valve body and recheck the diagnosis code.
|
|
|
(1)Check the mounting bolts for looseness, and the O-ring, solenoid valve and valve body for damage.
Replace the valve body assembly if the damages are thought to be irreparable.
|
|
|
(2)Test drive the vehicle.
|
|
|
(3)Check the diagnosis code.
|
|
|
Q.
Is the diagnosis code set?
|
|
|
Go to Step 7.
|
|
|
|
|
|
The inspection is complete.
|
|
|
|
|
|
STEP 6. Replace the A/T-ECU and then recheck the diagnosis code.
|
|
|
(2)Test drive the vehicle.
|
|
|
(3)Check the diagnosis code.
|
|
|
Q.
Is the diagnosis code set?
|
|
|
Go to Step 7.
|
|
|
|
|
|
The inspection is complete.
|
|
|
|
|
|
STEP 7. Check the A/T internal clutch and brake, and then recheck the diagnosis code.
|
|
|
(1)Check the following clutches or brakes according to the output diagnosis codes, replace if necessary.
- If diagnosis code P1779, P1780, P1781 are set individually or in a group, replace the underdrive clutch.
- If diagnosis code P1781, P1782 are set individually or in a group, replace the overdrive clutch.
- If diagnosis code P1784 is set, replace the reverse clutch.
- If diagnosis code P1779, P1784 are set individually or in a group, replace the low-reverse brake.
- If diagnosis code P1780, P1782 are set individually or in a group, replace the second brake.
- If diagnosis code P1779 is set, replace the one-way clutch.
|
|
|
(2)Test drive the vehicle.
|
|
|
(3)Check the diagnosis code.
|
|
|
Q.
Is the diagnosis code set?
|
|
|
Eliminate the cause of the noise.
|
|
|
|
|
|
The inspection is complete.
|
|
|
|
faq.Lancer-Club.ru