Toyota CH-R Service Manual: Check Bus 3 Lines for Short Circuit

Toyota CH-R Service Manual / Networking / Can Communication System / Check Bus 3 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the CAN main bus lines and/or CAN branch lines when the resistance between terminals 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom

Trouble Area

Resistance between terminals 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is below 54 Ω.
  • Short in CAN main bus lines
  • Short in CAN branch lines
  • Radio and display receiver assembly

    (for Radio and Display Type)

  • DCM (Telematics transceiver)

    (w/ Telematics Transceiver)

  • Central gateway ECU (network gateway ECU)
  • No. 3 CAN junction connector

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.

    Click here

  • 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.

    Click here

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

    DTC check procedure: Turn the ignition switch ON and wait at least approximately 60 seconds.

  • 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

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 IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the No. 3 CAN junction connector.

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

*a

Front view of wire harness connector

(to No. 3 CAN junction connector)

*b

to DCM (Telematics Transceiver)

(w/ Telematics Transceiver)

*c

to Radio and Display Receiver Assembly

(for Radio and Display Type)

*d

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

F114-8 (CANH) - F114-19 (CANL)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

DCM (Telematics transceiver)*1

F114-9 (CANH) - F114-20 (CANL)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

Radio and display receiver assembly*2

F114-10 (CANH) - F114-21 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

Central gateway ECU (network gateway ECU)

F114-11 (CANH) - F114-22 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

Central gateway ECU (network gateway ECU)
  • *1: w/ Telematics Transceiver
  • *2: for Radio and Display Type

Result

Proceed to

OK

A

NG (Line to central gateway ECU (network gateway ECU))

B

NG (Line to ECU or sensor)

C
A

REPLACE NO. 3 CAN JUNCTION CONNECTOR
C

GO TO STEP 3

B

2.

CHECK FOR SHORT IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

(a) Disconnect the F74 central gateway ECU (network gateway ECU) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

F114-10 (CANH) - F114-21 (CANL)

Cable disconnected from negative (-) battery terminal

1 MΩ or higher

F114-11 (CANH) - F114-22 (CANL)

Cable disconnected from negative (-) battery terminal

1 MΩ or higher

*a

Front view of wire harness connector

(to No. 3 CAN Junction Connector)

*b

to Central Gateway ECU (Network Gateway ECU)
OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

3.

CHECK FOR SHORT IN CAN BUS LINES (ECU OR SENSOR)

(a) Reconnect all wire harness connectors.

(b) Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited branch line is connected.

Click here

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

F74-6 (CA3H) - F74-21 (CA3L)

Cable disconnected from negative (-) battery terminal

54 to 69 Ω

HINT:

  • If the resistance becomes normal (between 54 and 69 Ω) when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.
  • If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short in the wire harness and repair or replace the wire harness or connector if necessary.

*a

Component with harness connected

(Central Gateway ECU (Network Gateway ECU))
OK

REPLACE ECU OR SENSOR
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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