Toyota CH-R Service Manual: Check Bus 4 Line for Short to GND

Toyota CH-R Service Manual / Networking / Can Communication System / Check Bus 4 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 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 7 (CA2L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom	Trouble Area
No resistance exists between terminal 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 7 (CA2L) 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 Central gateway ECU (network gateway ECU) Airbag sensor assembly Steering sensor Power steering ECU assembly Brake actuator assembly Occupant detection ECU (w/ Occupant Detection ECU) No. 5 CAN junction connector No. 4 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.
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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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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. 5 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the No. 5 CAN junction connector.

*1	DLC3	-	-
*a	Front view of wire harness connector (to No. 5 CAN Junction Connector)	*b	to No. 4 CAN Junction Connector
*c	to Central Gateway ECU (Network Gateway ECU)	*d	to Occupant Detection ECU (w/ Occupant Detection ECU)
*e	to Brake Actuator Assembly	-	-

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
F124-1 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	No. 4 CAN junction connector
F124-12 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	No. 4 CAN junction connector
F124-2 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Central gateway ECU (network gateway ECU)
F124-13 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Central gateway ECU (network gateway ECU)
F124-4 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Occupant detection ECU*1
F124-15 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Occupant detection ECU*1
F124-5 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Brake actuator assembly
F124-16 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Brake actuator assembly

*1: w/ Occupant Detection ECU

Result	Proceed to
OK	A
NG (Line to central gateway ECU (network gateway ECU))	B
NG (Line to No. 4 CAN junction connector)	C
NG (Line to ECU or sensor)	D

REPLACE NO. 5 CAN JUNCTION CONNECTOR

GO TO STEP 3

GO TO STEP 4

2.	CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 5 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.

DLC3

Front view of wire harness connector

(to No. 5 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

Standard Resistance:

Tester Connection	Condition	Specified Condition
F124-2 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
F124-13 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 5 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

3.	CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR)

(a) Disconnect the No. 4 CAN junction 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. 4 CAN Junction Connector)	*b	to Airbag Sensor Assembly
*c	to Steering Sensor	*d	to Power Steering ECU Assembly
*e	to No. 5 CAN Junction Connector	-	-

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
F123-1 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Airbag sensor assembly
F123-12 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Airbag sensor assembly
F123-5 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Steering sensor
F123-16 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Steering sensor
F123-6 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Power steering ECU assembly
F123-17 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Power steering ECU assembly
F123-7 (CANH) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	No. 5 CAN junction connector
F123-18 (CANL) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	No. 5 CAN junction connector

Result	Proceed to
OK	A
NG (Line to No. 5 CAN junction connector)	B
NG (Line to ECU or sensor)	C

REPLACE NO. 4 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - NO. 5 CAN JUNCTION CONNECTOR)

GO TO STEP 4

4.	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.

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DLC3

Component with harness connected

(Central Gateway ECU (Network Gateway ECU))

Standard Resistance:

Tester Connection	Condition	Specified Condition
F74-22 (CA2H) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
F74-7 (CA2L) - F41-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher

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.

REPLACE ECU OR SENSOR

REPAIR OR REPLACE HARNESS OR CONNECTOR

Check Bus 4 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 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal ...

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Toyota CH-R Service Manual: Check Bus 4 Line for Short to GND

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