Diagnostics with Phenomenon: Inspection

Trouble symptom: 

The steering wheel operation feels heavy.

Wiring diagram: 

Electric power steering system Ref. to WIRING SYSTEM>Electric Power Steering System>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK BATTERY  Check the battery. Ref. to Ref. to STARTING/CHARGING SYSTEMS(H4DO)>Battery>INSPECTIONSTARTING/CHARGING SYSTEMS(H4DOTC)>Battery>INSPECTION .

   Is the check result OK?

   Yes:  Go to  2

   No:  Charge or replace the battery.

2. CHECK BATTERY TERMINAL AND FUSE 

   Check the battery terminals and the fuse.

   Is the check result OK?

   Yes:  Go to  3

   No:  Repair or replace faulty parts.

3. CHECK WIRING HARNESS 
   1. Disconnect the connector. (B21, B52)
   2. Turn the ignition switch to ON.
   3. Using a tester and special tool harness, check the voltage between terminals.

   Connector & terminal 

   (B21) No. 2 (+) - Chassis ground (-):

   Is the voltage 12 V or more?

   Yes:  Go to  4

   No:  Repair the open circuit of harness or the poor contact of connector between the power steering control module and the battery.

4. CHECK GROUND CIRCUIT 
   1. Turn the ignition switch to OFF.
   2. Using a tester and special tool harness, check the resistance between terminals.

   Connector & terminal 

   (B21) No. 1 - Chassis ground:

   Is the resistance less than 1 Ω?

   Yes:  Go to  5

   No:  Repair the open circuit or poor contact of the harness between the power steering control module and chassis ground.

5. CHECK HARNESS 
   1. Turn the ignition switch to OFF.
   2. Disconnect the power steering control module connector (B76).
   3. Using a tester and special tool harness, check the resistance between harness terminals.

   Connector & terminal 

   (B52) No. 1 - (B76) No. 1:

   (B52) No. 2 - (B76) No. 2:

   Is the resistance less than 1 Ω?

   Yes:  Replace the steering gearbox. Ref. to POWER ASSISTED SYSTEM (POWER STEERING)>Electric Power Steering Gearbox

   No:  Repair or replace the harness.