POWER ASSIST SYSTEMS: POWER STEERING SYSTEM (for HV Model): C155A16,C155A17,C155B16,C155B17; Power Steering Motor "A" Supply Voltage Circuit Voltage Below Threshold; 2023 - 2025 MY Corolla Corolla HV [09/2022

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM10000000257FB
Model Year Start: 2023	Model: Corolla	Prod Date Range: [09/2022 - ]
Title: POWER ASSIST SYSTEMS: POWER STEERING SYSTEM (for HV Model): C155A16,C155A17,C155B16,C155B17; Power Steering Motor "A" Supply Voltage Circuit Voltage Below Threshold; 2023 - 2025 MY Corolla Corolla HV [09/2022 - ]

DTC

C155A16

Power Steering Motor "A" Supply Voltage Circuit Voltage Below Threshold

DTC

C155A17

Power Steering Motor "A" Supply Voltage Circuit Voltage Above Threshold

DTC

C155B16

Power Steering Motor "B" Supply Voltage Circuit Voltage Below Threshold

DTC

C155B17

Power Steering Motor "B" Supply Voltage Circuit Voltage Above Threshold

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	Power switch on (IG) 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	Power switch on (IG) 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	Power switch on (IG) 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	Power switch on (IG) again	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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 I42 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
I42-1 (PIG) - Body ground	Always	9 to 16 V

*a	Front view of wire harness connector (to Power Steering ECU Assembly)

Standard Resistance:

Tester Connection	Condition	Specified Condition
I42-2 (PGND) - Body ground	Always	Below 1 Ω

REPLACE POWER STEERING ECU ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR