Electronic Control System

Electronic Control Circuit:

ELECTRONIC CONTROL CIRCUIT

Electronic Control Components:

ELECTRONIC CONTROL COMPONENTS

Part 1:

Part 2:

TROUBLESHOOTING OF ELECTRONIC CONTROL SYSTEM

NOTE:
- If diagnostic code Nos. 42, 61, 62 or 63 occur, the overdrive indicator light will begin to blink immediately to warn the driver. However, an impact or shock may cause the blinking to stop; but, the code will still be retained in the ECT computer memory until canceled out.
- There is no warning for diagnostic code No. 64.
- In the event of a simultaneous malfunction of both No. 1 and No. 2 speed sensors, no diagnostic code will appear and the fail-safe system will not function. However, when driving in the D range, the transmission will not up-shift from first gear, regardless of the vehicle speed.

READ OF DIAGNOSTIC CODE




1. TURN IGNITION SWITCH AND OD SWITCH TO ON
Do not start the engine.

NOTE: Warning and diagnostic code can be read only when the overdrive switch is ON. If OFF the overdrive light will light continuously and will not blink.




2. SHORT TERMINAL ECT CIRCUIT
Using a service wire, short the service connector terminals ECT and E(1) of the service connector.

3. READ DIAGNOSTIC CODE






NOTE: Read the diagnostic code as indicated by the number of times the 0/D "OFF" light flashes.




a. If the system is operating normally, the light will blink on for 0.25 seconds at intervals of 0.25 seconds.







b. In the event of a malfunction, the light will blink once every 0.5 seconds. The number of blinks will equal the first number and, after a 1.5 second pause, the second number of the two digit diagnostic code.
If there are two or more codes, there will be a 2.5 second pause between each.

NOTE: In the event of several trouble codes occurring simultaneously, indication will begin from the smaller value and continue to the larger.

c. Remove the service wire from the service connector terminals ECT and E(1).

NOTE: If codes 62, 63, 64 appear, there is an electrical malfunction in the solenoid.
Causes due to mechanical failure, such as a stuck switch, will not appear.

CANCEL OUT DIAGNOSTIC CODE




1. After repair of the trouble area, the diagnostic code retained in memory by the ECT ECU must be canceled by removing the fuse DOME (20 A) for 10 seconds or more, depending on ambient temperature (the lower the temperature, the longer the fuse must be left out) with the ignition switch off.

NOTE:
- Cancellation can also be done by removing the battery negative (-) terminal, but in this case, other memory systems (clock, radio ETR, etc.) will also be canceled out.
- The diagnostic code can also be canceled out by disconnecting the ECT computer connector.
- If the diagnostic code is not canceled out, it will be retained by the ECT computer and appear along with a new code in event of future trouble.

2. After cancellation, perform a road test to confirm that a "normal code" is now read on the OD "OFF" light.

INSPECTION OF TERMINAL ECT VOLTAGE

1. INSPECT THROTTLE POSITION SENSOR SIGNAL




a. Turn the ignition switch to ON. Do not start the engine.
b. Connect a voltmeter to the terminals ECT and E(1) of the service connector.




c. While slowly depressing the accelerator pedal, check that terminal ECT voltage rises in sequentially.
If the voltage is in proportion to the throttle opening angle and does not change, there is a malfunction with the throttle position sensor or circuit.

2. INSPECT BRAKE SIGNAL
a. Depress the accelerator pedal until the terminal ECT indicates 8V.
b. Depress the brake pedal and check the voltage reading from the terminal ECT.

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 OD switch to "ON."
c. Place the pattern select switch in "Normal" and the shift selector into the D range.
d. During a road test (above 10 kph or 6 mph) check that voltage at the terminal ECT is as indicated below for each up-shift position.




e. If the voltage rises from 0 V to 7 V in the sequence shown, the control system is okay.
f. The voltage could rise anywhere between 0 V - 8 V before the vehicle reaches 10 kph (6 mph), the voltmeter indicates the current gear.

NOTE: Determine the gear position by a light shock or change in engine rpm when shifting.

INSPECTION OF ELECTRONIC CONTROL COMPONENTS

Terminals Of ECM/Pinouts Part 1:

Pinouts Part 2:

1. INSPECT VOLTAGE OF ECT COMPUTER CONNECTOR
a. Remove the center cluster.
b. Turn on the ignition switch.
c. Measure the voltage at each terminal.




2. INSPECT SOLENOID
a. Disconnect the connector from the ECT computer.
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.


NOTE: If there is foreign material in the solenoid valve, there will be no fluid control even with solenoid operation.




3. INSPECT NEUTRAL START SWITCH
a. Shift the lever into the L or 2 ranges.
b. Disconnect the connector near the starter motor.
c. Check that there is continuity between L, 2 and ground.







4. INSPECT THROTTLE POSITION SENSOR
Using an ohmmeter, check the resistance between each terminal.




5. INSPECT N0.2 SPEED SENSOR
a. Jack up one front wheel.
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 Ohms.




6. INSPECT NO. 1 SPEED SENSOR IN COMBINATION METER(ANALOG METER)
a. Remove the combination meter.
b. Connect an ohmmeter between terminals SPD (+) and SPD (-).
c. Revolve the meter shaft and check that the meter needle repeatedly deflects from 0 Ohm to Infinity Ohms.







7. INSPECT PATTERN SELECTION SWITCH
Inspect that there is continuity between 2 and each terminal.


NOTE: As there are diodes inside, be careful of the

8. INSPECT BRAKE SIGNAL
Check that the brake light comes on when the brake pedal is depressed.







9. INSPECT OD SWITCH
Inspect that there is continuity between terminals 1 and 3.




10. INSPECT LOCK-UP MECHANISM
a. Warm up the coolant and ATF.
b. Connect a voltmeter to the terminal ECT and E(1).
c. Select the normal pattern.
d. Drive at around 70 kph (43 mph) until 7, 5 or 3 V appears on the voltmeter (this is the lock-up range).
e. Depress the accelerator pedal and read the tachometer. If there is a big jump in engine rpm there is no lock-up.