NO.17 EXCESSIVE SHIFT SHOCK FROM N TO D OR N TO R POSITION/RANGE [AW6AX-EL]

id0503j6802200

17
Excessive shift shock from N to D or N to R position/range
DESCRIPTION
•  Strong shock felt when shifting from N to D or N to R position/range at idle.
POSSIBLE CAUSE
•  Shift shock may worsen when the fail-safe is operating. If no DTC is output, the shift shock may worsen due to poor operation of the control valve body or sticking of the clutch.
―  Clutch burnt (N→D: C1 clutch, N→R: C3 clutch or B2 brake)
•  Line pressure low
•  Incorrect accelerator opening signal
•  TFT sensor malfunction
•  Sensor ground malfunction
•  Shift solenoid C malfunction
•  Shift solenoid E malfunction
•  Line pressure control solenoid malfunction
•  Control valve body malfunction
―  Poor hydraulic operation (Malfunction in range change)
―  Idle speed high
―  Poor tightening torque of engine mount, exhaust mount
―  Line pressure high
―  Garage shift control is not learned
•  Initial learning did not perform
Note
•  Before following the troubleshooting steps, make sure that the Automatic Transaxle On-Board Diagnostic and Automatic Transaxle Basic Inspection are conducted. (See BASIC INSPECTION [AW6AX-EL].)

Diagnostic procedure

STEP

INSPECTION

ACTION
1
•  Does the shift shock occur only when the engine is cold?
Yes
Go to the next step.
No
Go to Step 3.
2
•  Inspect the TFT sensor and related wiring harness: vibration, intermittent open/short circuit.
•  Is it normal?
Yes
Go to the next step.
No
Repair or replace part if necessary.
3
•  Perform the initial learning procedure.
•  Does symptom eliminate?
Yes
Troubleshooting is completed.
No
Go to the next step.
4
•  Is the line pressure normal?
Yes
Go to the next step.
No
Repair or replace any malfunctioning parts according to the inspection results.
5
•  Is stall speed normal?
Yes
Go to the next step.
No
Repair or replace any malfunctioning parts according to the inspection results.
6
•  Stop the engine.
•  Inspect following solenoids.
―  Line pressure control solenoid
―  Shift solenoid C
―  Shift solenoid E
•  Are they normal?
Yes
Inspect the ATF condition.
•  If large amount of metal specks are found, overhaul the transaxle and repair or replace any malfunctioning parts.
(See Automatic Transaxle and Transfer Workshop Manual AW6A-EL AW6AX-EL.)
•  If a large amount of metal specks are not found, replace the control valve body.
No
•  Replace the control valve body.
7
•  Verify test results.
―  If normal, return to the diagnostic index to service any additional symptoms.
―  If the malfunction remains, inspect the related Service Information and perform repair or diagnosis.
•  If the vehicle is repaired, troubleshooting completed.
•  If the vehicle is not repaired or additional diagnostic information is not available, replace the TCM.


Initial Learning

Warning
•  When performing initial learning, be aware of other vehicles, people, and other impediments in order to avoid an accident.
Note
•  While self-learning control gradually reduces shock during normal driving, initial learning is performed to initially learn a certain amount of driving conditions.

1.  Warm-up

•  Increase the ATF temperature by leaving the vehicle idling or performing city driving. Verify that the ATF temperature is between 66—110 °C {151—230 °F}. If the ATF temperature is outside this range, work to bring it inside the range.
Caution
•  Do not raise the ATF temperature by stalling the engine.
Note
•  If the ATF temperature is not between 66—110 °C {151—230 °F}, initial learning cannot be performed.
Before learning, inspect for variable shift shock.

2.  Garage shift learning

•  With the vehicle standing still, depress the brake pedal and keep the selector lever in N position for 3 s. Then, shift the selector lever from the N position into D range, and maintain in this condition for 3 s. Repeat this procedure 5 times. Then repeat it 5 times in the same way for R position.

3.  Gear shift control learning

•  In D range, with the accelerator opening between 25—30%, drive until you reach 6th gear and a vehicle speed of 80 km/h {50 mph} or higher. Then, release the accelerator pedal and coast, and bring the vehicle to a stop in at least 60 s. Repeat this procedure 10 times.

4.  Inspect learning results

•  Verify that variable speed shock and shift shock have decreased compared to the conditions before learning.