No Shifting - Toyota MR2 1988 Repair Manual

AT-18 AUTOMATIC TRANSAXLE- Troubleshooting
Trouble No.2 No shifting
Warm up engine
Coolant temp: 80°C (176°F)
ATF temp: 50 - 80°C (122 - 176°F)
Read diagnostic code
(See page AT-23)
Malfunction
code(s)
Normal code
Connect a voltmeter to the service connector
terminals ECT and E
1 •
Does terminal ECT voltage vary with changes
in throttle opening?
Yes
No
Is voltage between ECT computer terminals
BK and GND as follows?
OV: Brake pedal released
12V: Brake pedal depressed
Yes
• Computer power source and ground faulty
• Throttle position signal faulty
• Terminal ECT wire open or short
Disconnect ECT computer connector and road
test. Does the transmission operate in the
respective gear when in the following ranges
while driving?
D range . . . Overdrive
2 range . . . 3rd gear
L range . . . 1 st gear
Yes
Continued on page AT -1 9
No
Proceed to trouble No. 1
(AT-17)
No
f - - - - - - - . . !
Brake signal
faulty
Transmission faulty