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Home >> Subaru >> 2006 >> Baja Turbo, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 16 (Automatic Transmission Diagnostics (4AT) (H4SO)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC 77 Lock-Up Duty Solenoid

DTC 77 Lock-Up Duty Solenoid

WARNING: This page is about a different variant/trim than selected.

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: 

Fig 1: Lock-Up Duty Solenoid - Wiring Diagram
G04990741Courtesy of SUBARU OF AMERICA, INC.
DIAGNOSTIC PROCEDURE CHART

Step Check Yes No
1 CHECK DTC.  Do multiple DTCs appear in the on-board diagnostics test mode? Go to another DTC. Go to step 2. 
2 CHECK HARNESS CONNECTOR BETWEEN TCM AND TRANSMISSION. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from TCM and transmission.
  3. Measure the resistance of harness between TCM and transmission connector.

    Connector & terminal 

    (B54) No. 16 - (B11) No. 13: 

 Is the resistance less than 1 Ω? Go to step 3.  Repair the open circuit in harness between TCM and transmission connector.
3 CHECK HARNESS CONNECTOR BETWEEN TCM AND TRANSMISSION. 
Measure the resistance of harness connector between TCM and chassis ground.
Connector & terminal 
(B54) No. 16 - Chassis ground: 		 Is the resistance more than 1 MΩ? Go to step 4.  Repair the short circuit in harness between TCM and transmission connector.
4 CHECK LOCK-UP DUTY SOLENOID. 
Measure the resistance between transmission connector receptacle's terminals.
Connector & terminal 
(74) No. 13 - No. 16: 		 Is the resistance 10 - 17 Ω? Go to step 5.  Go to step 11. 
5 PREPARE SUBARU SELECT MONITOR.  Do you have a Subaru Select Monitor? Go to step 8.  Go to step 6. 
6 CHECK OUTPUT SIGNAL EMITTED FROM TCM. 
  1. Connect the connectors to TCM and transmission.
  2. Lift-up the vehicle and place safety stand.
    NOTE: Raise all wheels off ground.
  3. 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.
  4. 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. < Ref. to CLEAR MEMORY MODE . >
  5. Measure the voltage between TCM connector and chassis ground.

    Connector & terminal 

    (B54) No. 16 (+) - Chassis ground (-): 

 Is the voltage more than 8.5 V? Go to step 7.  Go to step 10. 
7 CHECK OUTPUT SIGNAL EMITTED FROM TCM. 
  1. Return the engine to idling speed and move select lever to "N" range.
  2. Measure the voltage between TCM connector and chassis ground.

    Connector & terminal 

    (B54) No. 16 (+) - Chassis ground (-): 

 Is the voltage less than 0.5 V? 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. Go to step 10. 
8 CHECK OUTPUT SIGNAL EMITTED FROM TCM USING SUBARU SELECT MONITOR. 
  1. Connect the connectors to TCM and transmission.
  2. Lift-up the vehicle and place safety stand.
    NOTE: Raise all wheels off ground.
  3. Connect the Subaru Select Monitor to data link connector.
  4. Start the engine and turn Subaru Select Monitor switch to ON.
  5. 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.
  6. Read the data of lock-up duty solenoid using Subaru Select Monitor.
    • Lock-up duty solenoid is indicated in "%".
  7. 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. < Ref. to CLEAR MEMORY MODE . >
 Is the value 95%? Go to step 9.  Go to step 10. 
9 CHECK OUTPUT SIGNAL EMITTED FROM TCM USING SUBARU SELECT MONITOR. 
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. < Ref. to CLEAR MEMORY MODE . >
 Is the value 5%? 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. Go to step 10. 
10 CHECK POOR CONTACT.  Is there poor contact in lock-up duty solenoid circuit? Repair poor contact. Replace the TCM. < Ref. to TRANSMISSION CONTROL MODULE (TCM) . >
11 CHECK LOCK-UP DUTY SOLENOID (IN TRANSMISSION). 
  1. Remove the transmission connector from bracket.
  2. Drain the ATF.
    CAUTION: Do not drain the ATF until it cools down.
  3. Remove the oil pan and disconnect connector from lock-up duty solenoid.
  4. Measure the resistance between lock-up duty solenoid connector and transmission ground.

    Terminals 

    No. 1 - Transmission ground: 

 Is the resistance 10 - 17 Ω? Go to step 12.  Replace the lockup duty solenoid. < Ref. to SHIFT SOLENOIDS, DUTY SOLENOIDS AND ATF TEMPERATURE SENSOR . >
12 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? Go to step 13.  Repair the open circuit in harness between TCM and transmission connector.
13 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? 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. Repair the short circuit in harness between lock-up duty solenoid and transmission connector.
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