Toyota CH-R Service Manual: Check Bus 2 Line for Short to +B

Toyota CH-R Service Manual / Networking / Can Communication System / Check Bus 2 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Symptom

Trouble Area

No resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

  • Short to +B in CAN main bus line
  • Short to +B in CAN branch line
  • Central gateway ECU (network gateway ECU)
  • ECM

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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 (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
  • After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) 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 blind spot monitor system on using the blind spot monitor main switch (ON/OFF switch), turn the cruise control main switch on, turn the LDA main switch on and then drive the vehicle at a speed of 60 km/h (37 mph) or more for approximately 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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  • Before replacing the ECM, refer to Registration.*1

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  • *1: w/ Smart Key System

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 SHORT TO +B IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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

(b) Disconnect the central gateway ECU (network gateway ECU) connector.

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

*1

DLC3

-

-

*a

Front view of wire harness connector

(to Central Gateway ECU (Network Gateway ECU))

*b

to ECM

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

F74-18 (CA4H) - F41-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

ECM

F74-17 (CA4L) - F41-16 (BAT)

OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

2.

CHECK FOR SHORT TO +B IN CAN BUS LINE (ECM - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

(a) Disconnect the A38 ECM connector.

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

*1

DLC3

-

-

*a

Front view of wire harness connector

(to Central Gateway ECU (Network Gateway ECU))

*b

to ECM

Standard Resistance:

Tester Connection

Condition

Specified Condition

F74-18 (CA4H) - F41-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

F74-17 (CA4L) - F41-16 (BAT)

OK

REPLACE ECM

NG

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (ECM - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

    Open in Bus 2 Main Bus Line
    DESCRIPTION There may be an open circuit in one of the CAN main bus lines when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is 70 Ω o ...

    Check Bus 2 Line for Short to GND
    DESCRIPTION There may be a short circuit between one of the CAN bus lines and GND when there is no resistance between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and termi ...

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