Inspection Procedure 20: Shock is significant at shifting from N to R

COMMENTS ON TROUBLE SYMPTOM

If a strong shock occurs when the selector lever is shifted from N to R, the cause is probably an immixing of A/T fluid other than the specified one, a malfunction of the shift solenoid No.1 system, line pressure control solenoid system, lock-up solenoid system, stop lamp switch system, mounting (engine mounting and transmission mounting insulator), or valve body.

note

As a cause of shock, an engine system malfunction, driveshaft malfunction (damage, wear, looseness, large deflection), or suspension malfunction (looseness) is suspected. However, in this item, it shall be presupposed that there is no abnormality to the above.

PROBABLE CAUSES

Malfunction of shift solenoid No.1 system
Malfunction of mounting (engine mounting and transmission mounting insulator)
Malfunction of stop lamp switch system
Immixing of A/T fluid other than the specified one
Malfunction of valve body (line pressure control solenoid, lock-up solenoid)
Malfunction of the A/T-ECU
A/T internal error (clutch C3, brake B1/B4, one-way clutch F1, etc.)

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test

Item 1: Shift solenoid No.1

OK: Operating sound can be heard.

Q. Is the check result normal?

	Go to Step 2.

	Repair the shift solenoid No.1 system.

STEP 2. Mounting check

Check the engine mounting and transmission mounting insulator for damage and any faults.

Q. Is the check result normal?

	Go to Step 3.

	Repair or replace the engine mounting and transmission mounting insulator.

STEP 3. Stop lamp switch system check

The stop lamps should illuminate when the brake pedal is depressed, and extinguish when released.

Q. Is the check result normal?

	Go to Step 4.

	Refer to stop lamp switch system (Refer to GROUP 54A - ETACS - Troubleshooting, Input Signal Procedures).

STEP 4. A/T fluid change

Replace the A/T fluid. Then, check the trouble symptom again.

Q. Is the trouble symptom reproduced?

	Go to Step 5.

	This diagnosis is complete.

STEP 5. Valve body replacement

Replace the valve body. Then, check the trouble symptom again.

Q. Is the trouble symptom reproduced?

	Go to Step 6.

	This diagnosis is complete.

STEP 6. A/T-ECU replacement

Replace the A/T-ECU. Then, check the trouble symptom again.

Q. Is the trouble symptom reproduced?

	Check the clutches and brakes for 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.