Toyota Yaris: Power Steering System / Power Steering Motor "A" Supply Voltage Circuit Voltage Below Threshold (C155A16,C155A17,C155B16,C155B17)

Toyota Yaris XP210 (2020-2025) Reapir and Service Manual / Steering / Power Assist Systems / Power Steering System / Power Steering Motor "A" Supply Voltage Circuit Voltage Below Threshold (C155A16,C155A17,C155B16,C155B17)

DESCRIPTION

If a problem occurs in the system, the power source relay circuit and the motor relay circuit are shut off to stop power assist. The ECU must be replaced when there is a problem with the relays because the relays are built into the ECU.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Return-to-normal Condition	Note
C155A16	Power Steering Motor "A" Supply Voltage Circuit Voltage Below Threshold	Motor "1" PIG voltage is 3.6 V or less	EPS fuse PIG power source circuit Power steering ECU assembly	EPS warning light: Comes on	Ignition switch ON again	-
C155A17	Power Steering Motor "A" Supply Voltage Circuit Voltage Above Threshold	Diagnosis Condition: IG ON Malfunction Status: Motor "1" PIG voltage is 19.6 V or more	EPS fuse PIG power source circuit Power steering ECU assembly	EPS warning light: Comes on	Ignition switch ON again	-
C155B16	Power Steering Motor "B" Supply Voltage Circuit Voltage Below Threshold	Motor "2" PIG voltage is 3.6 V or less	EPS fuse PIG power source circuit Power steering ECU assembly	EPS warning light: Comes on	Ignition switch ON again	-
C155B17	Power Steering Motor "B" Supply Voltage Circuit Voltage Above Threshold	Diagnosis Condition: IG ON Malfunction Status: Motor "2" PIG voltage is 19.6 V or more	EPS fuse PIG power source circuit Power steering ECU assembly	EPS warning light: Comes on	Ignition switch ON again	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When the power steering ECU assembly has been replaced, perform Power Steering ECU Initial Setting (assist map writing).
Click here
Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - BODY GROUND)

(a) Disconnect the H2 power steering ECU assembly connectors.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection	Condition	Specified Condition
H2-1 (PIG) - Body ground	Engine running	4.5 to 5.5 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
H2-2 (PGND) - Body ground	Always	Below 1 Ω

REPLACE POWER STEERING ECU ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR

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