Electronic Control System
PRECAUTIONDo not open the cover or the case of the ECU and various computer unless absolutely necessary. (If the IC terminals are touched the IC may be destroyed by static electricity.)
Electronic Control Circuit:
ELECTRONIC CONTROL CIRCUIT
Electronic Control Components:
ELECTRONIC CONTROL COMPONENTS
TROUBLESHOOTING FLOW-CHART
Part 1:
Part 2:
Trouble No.1 No Shifting
Trouble No.2 Shift point too high or too low
Trouble No.3 No up-shift to overdrive (After warm-up)
Trouble No.4 No lock-up (After warm-up)
INSPECTION OF T(T) TERMINAL VOLTAGE
1. INSPECT THROTTLE POSITION SENSOR SIGNAL
a. Turn the ignition switch to ON. Do not start the engine.
b. Connect a voltmeter to check connector terminals T(T) and E(1).
c. While slowly depressing the accelerator pedal, check that T(T) terminal voltage rises in sequence.
If the voltage does not change in proportion to the throttle opening angle, there is a malfunction in the throttle position sensor or circuit.
2. INSPECT BRAKE SIGNAL
a. Depress the accelerator pedal until the T(T) terminal indicates 8V.
b. Depress the brake pedal and check the voltage reading from the T(T) terminal.
Brake pedal depressed...... 0V
Brake pedal released......... 8V
If not as indicated, there is a malfunction in either the stop light switch or circuit.
3. INSPECT EACH UP-SHIFT POSITION
a. Warm up the engine.
Coolant temperature: 80 °C (176 °F)
b. Turn the O/D switch to "ON".
c. Place the pattern select switch in "Normal" and the shift lever into the D range.
d. During a road test (above 10 km/h or 6 mph) check that voltage at the T(T) terminal is as indicated below for each up-shift position.
If the voltage rises from 0V to 7V in the sequence shown, the control system is okay.
The chart shows the voltmeter reading and corresponding gears.
HINT: Determine the gear position by a light shock or change in engine rpm when shifting. The lock-up clutch will turn ON only infrequently during normal 2nd and 3rd gear operation. To trigger this action, press the accelerator pedal to 50% or more of its stroke. At less than 50%, the voltage may change in the sequence 2V - 4V - 6V - 7V.
INSPECTION OF ELECTRONIC CONTROL COMPONENTS
Part 1:
Part 2:
1. INSPECT VOLTAGE OF ECT ECU CONNECTOR
a. Remove the cowl side trim of passenger side.
b. Turn on the ignition switch.
c. Measure the voltage at each terminal.
2. INSPECT SOLENOID
a. Disconnect the connector from the ECT ECU.
b. Measure the resistance between S(1), S(2), S(L) and ground.
STD: 11 - 15 ohms
c. Apply battery voltage to the solenoid. Check that an operation noise can be heard from the solenoid.
3. CHECK SOLENOID SEALS
If there is foreign material in the solenoid valve, there will be no fluid control even with solenoid operation.
a. Check No.1 and No.2 solenoid valves.
- Check that the solenoid valve does not leak when low-pressure compressed air is applied.
- When supply battery voltage to the solenoid, check that the solenoid valve opens.
b. Check the lock-up solenoid valve.
- Applying 5 kg/sq.cm (71 psi, 490 kPa) of compressed air, check that the solenoid valve opens.
- When supply battery voltage to the solenoid, check that the solenoid valve does not leak the air.
If a malfunction is found during voltage inspection (step 1.), inspect the components listed below.
4. INSPECT NEUTRAL START SWITCH
5. INSPECT THROTTLE POSITION SENSOR
Using an ohmmeter, check the resistance between each terminal.
6. (w/o A.B.S.) INSPECT NO.2 SPEED SENSOR
a. Jack up the rear wheel on one side.
b. Connect an ohmmeter between the connector and ground.
c. Spin the wheel and check that the meter needle deflects from 0 ohm to infinity ohm.
HINT: For vehicles with A.B.S., the A.B.S. rear speed sensor is used by the ECT instead of the No.2 speed sensor.
7. INSPECT NO.1 SPEED SENSOR IN COMBINATION METER
a. Remove the combination meter.
b. Connect an ohmmeter between terminals A and B.
c. Revolve the meter shaft and check that the meter needle repeatedly deflects from 0 ohm to infinity ohm.
8. INSPECT PATTERN SELECT SWITCH
Inspect that there is continuity between 2 and each terminal.
HINT: As there are diodes inside, be careful of the tester probe polarity.
9. INSPECT O/D SWITCH
Inspect that there is continuity between terminals 1 and 3.
10. INSPECT WATER TEMPERATURE SENSOR