Electronic Power Steering System Diagnosis System

Connecting the intelligent tester to the vehicle and reading various data output from the power steering ECU assembly is the only difference between usual troubleshooting procedures and those for a vehicle with a diagnostic system.
The power steering ECU assembly records DTCs when the ECU detects a malfunction in the computer itself or in its circuits.
To check the DTCs, connect the intelligent tester to the DLC3. The intelligent tester enables you to erase the DTCs and check the freeze frame data and various forms of steering data.

Check the DLC3.
The power steering ECU assembly uses CAN and ISO 15765-4 communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.

HINT:

Connect the intelligent tester cable to the DLC3, turn the engine switch on (IG), and attempt to use the tester. If the screen displays a communication error message, a problem exists on the vehicle side or the tester side.

1. If communication is normal when connecting the tester to another vehicle, inspect the DLC3 on the original vehicle.
   
2. If communication is still not possible when connecting the tester to another vehicle, the problem is probably in the tester itself. Consult the Service Department listed in the tester's operator's manual.
   

Check that the PS warning light comes on when the engine switch is turned on (IG) and goes off in approximately 3 seconds.

If the warning light does not come on or remains on, inspect the PS warning light circuit.