Power Steering. Electronic Power Steering System Eps Warning Light Circuit

When the power source voltage to the power steering ECU (terminals IG and PIG) drops, required steering effort increases and the P/S warning light turns on.

1.CHECK DTC

Using the intelligent tester, check for DTCs and confirm that there are no problems in the CAN communication system.
OK:
CAN DTCs are not output.

GO TO CAN COMMUNICATION SYSTEM

OK

2.READ VALUE USING INTELLIGENT TESTER (IG POWER SUPPLY)

Connect the intelligent tester to the DLC3.

Turn the ignition switch on (IG) and press the intelligent tester main switch ON.

Select the item "IG Power Supply" in the Data List and read the value displayed on the intelligent tester.

Power steering ECU:

Tester Display
Measurement Item/Range
Normal Condition
Specified Condition
IG Power Supply
ECU power source voltage:
Min.: 0 V
Max.: 20.1531 V
Ignition switch on (IG)
10 to 14 V
OK:
The normal condition value is displayed on the intelligent tester.

Go to step 5

NG

3.INSPECT FUSE (ECU-IG1)

Remove the ECU-IG1 fuse from the instrument panel junction block.

Measure the resistance of the fuse.
Standard resistance:
Below 1 Ω

CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE

OK

4.CHECK WIRE HARNESS (POWER STEERING ECU - BATTERY)

Disconnect the A2 and E21 ECU connectors.

Measure the voltage of the wire harness side connectors.
Standard voltage:
Tester Connection
Condition
Specified Condition
E21-5 (IG) - A2-2 (PGND)
Ignition switch on (IG)
10 to 14 V

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

5.READ VALUE USING TECHSTREAM (PIG POWER SUPPLY)

Connect the intelligent tester to the DLC3.

Turn the ignition switch on (IG) and press the intelligent tester main switch ON.

Select the item "PIG Power Supply" in the Data List and read the value displayed on the intelligent tester.

Power steering ECU:

Tester Display
Measurement Item/Range
Normal Condition
Specified Condition
PIG Power Supply
PIG power supply:
Min.: 0 V
Max.: 20.1531 V
Power steering in operation
10 to 14 V

Go to step 8

NG

6.INSPECT FUSE (EMPS)

Remove the EMPS fuse from the engine room No. 1 relay block.

Measure the resistance of the fuse.
Standard resistance:
Below 1 Ω

CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE

OK

7.CHECK WIRE HARNESS (POWER STEERING ECU - BATTERY)

Disconnect the A2 ECU connector.

Measure the voltage of the wire harness side connector.
Standard voltage:
Tester Connection
Specified Condition
A2-1 (PIG) - A2-2 (PGND)
10 to 14 V

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

8.PERFORM ACTIVE TEST USING INTELLIGENT TESTER (METER GAUGE SYSTEM)

Perform the Active Test of the combination meter using the intelligent tester.

Combination meter
Item
Test Details
Diagnostic Note
Indicat. EPS
P/S indicator light
ON/OFF
-

Combination meter
Item	Test Details	Diagnostic Note
Indicat. EPS	P/S indicator light ON/OFF	-

Check that the P/S warning light operates in accordance with the Active Test.
HINT:
Reconnect the connectors and restore the vehicle to its previous condition before checking the combination meter.

REPLACE COMBINATION METER ASSEMBLY

REPLACE POWER STEERING ECU

Tester Display	Measurement Item/Range	Normal Condition	Specified Condition
IG Power Supply	ECU power source voltage: Min.: 0 V Max.: 20.1531 V	Ignition switch on (IG)	10 to 14 V

Tester Connection	Condition	Specified Condition
E21-5 (IG) - A2-2 (PGND)	Ignition switch on (IG)	10 to 14 V

Tester Connection	Specified Condition
A2-1 (PIG) - A2-2 (PGND)	10 to 14 V