Road Test - Toyota MR2 1988 Repair Manual

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• Shock
• Slippage
AUTOMATIC TRANSAXLE- Troubleshooting
AT077
8
8
8 8
I
AT0771
Road Test
CAUTION: Perform the test at normal operating fluid
temperature (50 - 80°C or 122 - 176°F).
1. D RANGE TEST IN NORM AND PWR PATTERN
RANGES
Shift into the 0 range and hold accelerator pedal constant
at 50% and 100% throttle valve opening positions. Push in
one of the pattern selection buttons with 00 the switch
ON and check the following:
(a) 1-2, 2-3, 3-0D and lock-up up-shifts should take
place, and shift points should conform to those
shown in the automatic shift diagram.
NOTE:
( 1 ) There is no 00 up-shift when coolant temperature is
below 50°C (122°F).
(2) There is no lock-up when the vehicle speed is 10 km/
h
(6
mph) less than the set cruise control speed.
EVALUATION
(1) If there is no 1 - 2 up-shift:
• No. 2 solenoid is stuck
• 1 -2 shift valve is stuck
(2) If there is no 2 - 3 up-shift:
• No. 1 solenoid is stuck
• 2-3 shift valve is stuck
(3) If there is no 3 - OD up-shift (throttle valve opening
1/2):
• 3-0D shift valve is stuck
(4) If the shift point is defective:
• Throttle valve, 1-2 shift valve, 2-3 shift valve, 3-
00 shift valve ect., are defective.
(5) If the lock-up is defective:
• No. 3 solenoid is stuck
• Lock-up relay valve is stuck
(b) In the same manner, check the shock and the slip at 1
- 2, 2 - 3 and 3 - OD up-shifts.
EVALUATION
If the shock is severe:
• Line pressure is too high
• Accumulator is defective
• Check ball is defective