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DTC 77 LOCK-UP DUTY SOLENOID

DTC 77 LOCK-UP DUTY SOLENOID

DIAGNOSIS:

The output signal circuit of lock-up duty solenoid is open or shorted.

TROUBLE SYMPTOM:

No “lock-up” (after engine warm-up).

WIRING DIAGRAM:


CHECK HARNESS CONNECTOR BETWEEN TCM AND TRANSMISSION.

Turn the ignition switch to OFF.

Disconnect the connector from TCM and transmission.

Measure the resistance of harness between TCM and transmission connector.

Connector & terminal

(B54) No. 7 — (B11) No. 13:

Is the resistance less than 1 Ω?

Yes


No

Repair the open circuit in harness between TCM and transmission connector.


CHECK HARNESS CONNECTOR BETWEEN TCM AND TRANSMISSION.

Measure the resistance of harness connector between TCM and chassis ground.

Connector & terminal

(B54) No. 7 — Chassis ground:

Is the resistance more than 1 MΩ?

Yes


No

Repair the short circuit in harness between TCM and transmission connector.


CHECK LOCK-UP DUTY SOLENOID.

Measure the resistance between transmission connector receptacle’s terminals.

Connector & terminal

(T4) No. 13 — No. 16:

Is the resistance 10 — 17 Ω?

Yes


No


CHECK OUTPUT SIGNAL EMITTED FROM TCM USING Vehicle Diagnostic Interface.

Connect the connectors to TCM and transmission.

Lift-up the vehicle and support with rigid racks.

Note

Raise all wheels off ground.


Connect the Vehicle Diagnostic Interface to data link connector.

Start the engine and turn Vehicle Diagnostic Interface switch to ON.

Start the engine and warm-up the transmission until ATF temperature is above 80°C (176°F).

Note

If ambient temperature is below 0°C (32°F), drive the vehicle until ATF reaches its operating temperature.


Read the data of lock-up duty solenoid using Vehicle Diagnostic Interface.


• Lock-up duty solenoid is indicated in “%”.


Move the selector lever to “D” range and slowly increase vehicle speed to 75 km/h (47 MPH). Wheels will lock-up.

Note

The speed difference between front and rear wheels may light the ABS warning light, but this indicates no malfunction. When AT control diagnosis is finished, perform the ABS memory clearance procedure of on-board diagnostics system.


Is the value 95%?

Yes


No


CHECK OUTPUT SIGNAL EMITTED FROM TCM USING Vehicle Diagnostic Interface.

Return the engine to idling speed and move selector lever to “N” range.

Note

The speed difference between front and rear wheels may light the ABS warning light, but this indicates no malfunction. When AT control diagnosis is finished, perform the ABS memory clearance procedure of on-board diagnostics system.


Is the value 5%?

Yes

Even if the AT OIL TEMP warning light blinks, the circuit has returned to a normal condition at this time. A temporary poor contact of the connector or harness may be the cause. Repair the harness or connector in TCM and transmission.


No


CHECK POOR CONTACT.

Is there poor contact in lock-up duty solenoid circuit?

Yes

Repair poor contact.


No

Replace the TCM.


CHECK LOCK-UP DUTY SOLENOID (IN TRANSMISSION).

Remove the transmission connector from bracket.

Drain the ATF.

Important

Do not drain the ATF until it cools down.


Remove the oil pan and disconnect connector from lock-up duty solenoid.

Measure the resistance between lock-up duty solenoid connector and transmission ground.

Terminals

No. 1 — Transmission ground:

Is the resistance 10 — 17 Ω?

Yes


No

Replace the lock-up duty solenoid.


CHECK HARNESS CONNECTOR BETWEEN LOCK-UP DUTY SOLENOID AND TRANSMISSION.

Measure the resistance of harness between lock-up duty solenoid and transmission connector.

Connector & terminal

(T4) No. 13 — (AT3) No. 1:

Is the resistance less than 1 Ω?

Yes


No

Repair the open circuit in harness between TCM and transmission connector.


CHECK HARNESS CONNECTOR BETWEEN LOCK-UP DUTY SOLENOID AND TRANSMISSION.

Measure the resistance of harness between transmission connector and transmission ground.

Connector & terminal

(T4) No. 13 — Transmission ground:

Is the resistance more than 1 MΩ?

Yes

Even if the AT OIL TEMP warning light blinks, the circuit has returned to a normal condition at this time. A temporary poor contact of the connector or harness may be the cause. Repair the harness or connector in lock-up duty solenoid and transmission.


No

Repair the short circuit in harness between lock-up duty solenoid and transmission connector.