Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001GVYW
Model Year Start: 2020 Model: Corolla Prod Date Range: [01/2019 - 09/2022]
Title: NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): Millimeter Wave Radar Sensor Communication Stop Mode; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

Millimeter Wave Radar Sensor Communication Stop Mode

DESCRIPTION

Detection Item

Symptom

Trouble Area

Millimeter Wave Radar Sensor Communication Stop Mode

Any of the following conditions are met:

  • Communication stop for "Front Radar" is indicated on the "Communication Bus Check" screen of the Techstream.

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  • Communication stop history for "Front Radar" is indicated on the "Communication Bus Check (Detail)" screen of the Techstream. (The Lost Communication Time value for "Front Radar" is 6 or more.)

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  • Communication system DTCs (DTCs that start with U) that correspond to "Millimeter Wave Radar Sensor Communication Stop Mode" in "DTC Combination Table" are output.

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  • Millimeter wave radar sensor assembly branch line or connector
  • Power source circuit of millimeter wave radar sensor assembly
  • Millimeter wave radar sensor assembly ground circuit
  • Millimeter wave radar sensor 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.

    Click here 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]; NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): HOW TO PROCEED WITH TROUBLESHOOTING

  • Before measuring the resistance of the CAN bus, turn the power 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 turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

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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 power switch on (IG) 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.

    Click here 2020 MY Corolla Corolla HV [01/2019 - 04/2020]; NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): DIAGNOSIS SYSTEM 2021 - 2022 MY Corolla Corolla HV [04/2020 - 09/2022]; NETWORKING: CAN COMMUNICATION SYSTEM (for HV Model): DIAGNOSIS SYSTEM

  • Inspect the fuses for circuits related to this system before performing the following procedure.

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 (MILLIMETER WAVE RADAR SENSOR ASSEMBLY BRANCH LINE)

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

(b) Disconnect the A1 millimeter wave radar sensor assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A1-3 (CA2H) - A1-2 (CA2L)

Cable disconnected from negative (-) auxiliary battery terminal

54 to 69 Ω

*a

Front view of wire harness connector

(to Millimeter Wave Radar Sensor Assembly)
NG

REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (MILLIMETER WAVE RADAR SENSOR ASSEMBLY)
OK

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

A1-1 (SGND) - Body ground

Cable disconnected from negative (-) auxiliary battery terminal

Below 1 Ω

*a

Front view of wire harness connector

(to Millimeter Wave Radar Sensor Assembly)

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A1-8 (IGB) - Body ground

Power switch on (IG)

11 to 14 V
OK

REPLACE MILLIMETER WAVE RADAR SENSOR ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)