Toyota CH-R Service Manual: Check Bus 3 Line for Short to GND

Toyota CH-R Service Manual / Networking / Can Communication System / Check Bus 3 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 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 21 (CA3L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom

Trouble Area

No resistance exists between terminal 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 21 (CA3L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.
  • Short to ground in CAN main bus line
  • Short to ground in CAN branch line
  • 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 TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the F114 No. 3 CAN junction connector.

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

*1

DLC3

-

-

*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) - F41-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

DCM (Telematics transceiver)*1

F114-19 (CANL) - F41-4 (CG)

F114-9 (CANH) - F41-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

Radio and display receiver assembly*2

F114-20 (CANL) - F41-4 (CG)

F114-10 (CANH) - F41-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

Central gateway ECU (network gateway ECU)

F114-21 (CANL) - F41-4 (CG)

F114-11 (CANH) - F41-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

Central gateway ECU (network gateway ECU)

F114-22 (CANL) - F41-4 (CG)
  • *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 TO GND IN CAN BUS LINE (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.

*1

DLC3

-

-

*a

Front view of wire harness connector

(to No. 3 CAN Junction Connector)

*b

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection

Condition

Specified Condition

F114-10 (CANH) - F41-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

F114-21 (CANL) - F41-4 (CG)

F114-11 (CANH) - F41-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

F114-22 (CANL) - F41-4 (CG)
OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

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

3.

CHECK FOR SHORT TO GND IN CAN BUS LINE (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 bus line shorted to GND is connected.

Click here

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

*1

DLC3

-

-

*a

Component with harness connected

(Central Gateway ECU (Network Gateway ECU))

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

F74-6 (CA3H) - F41-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

F74-21 (CA3L) - F41-4 (CG)

HINT:

  • If the resistance changes to 200 Ω or higher 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 to ground in the wire harness and repair or replace the wire harness or connector if necessary.
OK

REPLACE ECU OR SENSOR
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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