Toyota Yaris: Can Communication System / Power Steering ECU Communication Stop Mode

Toyota Yaris XP210 (2020-2026) Reapir and Service Manual / Power Source & Network / Networking / Can Communication System / Power Steering ECU Communication Stop Mode

DESCRIPTION

Detection Item	Symptom	Trouble Area
Power Steering ECU Communication Stop Mode	Communication stop for "Power Steering (EPS)" is indicated on the "Communication Bus Check" screen of the GTS. Click here	Power steering ECU assembly main line or connector Power source circuit of power steering ECU assembly Power steering ECU assembly ground circuit Power steering ECU assembly

Detection Item

Symptom

Trouble Area

Power Steering ECU Communication Stop Mode

Communication stop for "Power Steering (EPS)" is indicated on the "Communication Bus Check" screen of the GTS.

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Power steering ECU assembly main line or connector
Power source circuit of power steering ECU assembly
Power steering ECU assembly ground circuit
Power steering ECU assembly

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

NOTICE:

Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.
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Before measuring the resistance of the CAN bus, turn the ignition switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
After the ignition switch is turned off, there may be a waiting time before disconnecting the negative (-) auxiliary battery terminal.
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When disconnecting and reconnecting the auxiliary battery, there is an automatic learning function that completes learning when the respective system is used.
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Some parts must be initialized and set when replacing or removing and installing parts.
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After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.
DTC check procedure: Turn the ignition switch to ON and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 5 minutes or more.
After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.
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HINT:

Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.
When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE

1.	CHECK FOR OPEN IN CAN BUS LINES (POWER STEERING ECU ASSEMBLY MAIN LINE)

(a) Disconnect the cable from the negative (-) auxiliary battery terminal.

(b) Disconnect the power steering ECU assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
H1-7 (CANH) - H1-8 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	108 to 132 Ω

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

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (POWER STEERING ECU ASSEMBLY)

2.	CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
H2-2 (PGND) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

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

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

3.	CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

(a) Reconnect the cable to the negative (-) auxiliary battery terminal.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
H1-1 (IG) - Body ground	Ignition switch ON	10.5 to 16 V

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

REPLACE POWER STEERING ECU ASSEMBLY

GO TO STOP AND START SYSTEM (BACKUP BOOST CONVERTER CIRCUIT)

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