EPS Warning Light Circuit: Procedure

1. Using a Techstream, check for DTCs and confirm that there are no problems in the CAN communication system.

   OK

   DTCs are not output.

NG → See step   6 

OK: Go to next step 

1. Connect a Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Chassis / EMPS / Data List.
5. Select the item "IG Power Supply" in the Data List and read the value displayed on the Techstream.
   EMPS:
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   IG Power Supply	ECU power source voltage: Minimum: 0 V, Maximum: 20.1531 V	11 to 14 V: Ignition switch ON	-

   OK

   The normal condition value is displayed on the Techstream.

   HINT: 

   If the voltage is not standard value, inspect the IG power source circuit. Refer to DTC C1551/51: IG Power Supply Voltage Malfunction .

NG → See step   8 

OK: Go to next step 

1. Disconnect the connectors from the power steering ECU.
   Fig 1: Measuring Voltage Of Power Steering ECU Connectors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   F30-6 (IG) - Body ground	Ignition switch ON	11 to 14 V

3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   A19-2 (PGND) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Replace the power steering ECU. Refer to REMOVAL .
   NOTE:

   After replacing the power steering ECU, perform the torque sensor zero point calibration. Refer to CALIBRATION .

NEXT: Go to next step 

1. Check that the PS warning light comes on for 3 seconds after the ignition switch is turned to ON.

   OK

   The PS warning light operates normally.

NG → See step   7 

OK → END