Toyota CH-R Service Manual: Check Bus 4 Lines for Short Circuit

Toyota CH-R Service Manual / Networking / Can Communication System / Check Bus 4 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 22 (CA2H) and 7 (CA2L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom	Trouble Area
Resistance between terminals 22 (CA2H) and 7 (CA2L) of the central gateway ECU (network gateway ECU) is below 54 Ω.	Short in CAN main bus lines Short in CAN branch lines 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 IN CAN BUS LINES (NO. 5 CAN JUNCTION CONNECTOR)

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

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

Front view of wire harness connector

(to No. 5 CAN Junction Connector)

to No. 4 CAN Junction Connector

to Central Gateway ECU (Network Gateway ECU)

to Occupant Detection ECU

(w/ Occupant Detection ECU)

to Brake Actuator Assembly

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
F124-1 (CANH) - F124-12 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 4 CAN junction connector
F124-2 (CANH) - F124-13 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Central gateway ECU (network gateway ECU)
F124-4 (CANH) - F124-15 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Occupant detection ECU*1
F124-5 (CANH) - F124-16 (CANL)	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 5

2.	CHECK FOR SHORT IN CAN BUS LINES (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.

Standard Resistance:

Tester Connection	Condition	Specified Condition
F124-2 (CANH) - F124-13 (CANL)	Cable disconnected from negative (-) battery terminal	1 MΩ or higher

Front view of wire harness connector

(to No. 5 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

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

3.	CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR)

(a) Reconnect the F124 No. 5 CAN junction connector.

(b) Disconnect the No. 4 CAN junction connector.

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

to Airbag Sensor Assembly

to Steering Sensor

to Power Steering ECU Assembly

to No. 5 CAN Junction Connector

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
F123-1 (CANH) - F123-12 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Airbag sensor assembly
F123-5 (CANH) - F123-16 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Steering sensor
F123-6 (CANH) - F123-17 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Power steering ECU assembly
F123-7 (CANH) - F123-18 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 5 CAN junction connector

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

REPLACE NO. 6 CAN JUNCTION CONNECTOR

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

GO TO STEP 5

4.	CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR - AIRBAG SENSOR ASSEMBLY)

(a) Disconnect the F70 airbag sensor assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
F123-1 (CANH) - F123-12 (CANL)	Cable disconnected from negative (-) battery terminal	1 MΩ or higher

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

to Airbag Sensor Assembly

REPLACE AIRBAG SENSOR ASSEMBLY

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - AIRBAG SENSOR ASSEMBLY)

5.	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.

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Standard Resistance:

Tester Connection	Condition	Specified Condition
F74-22 (CA2H) - F74-7 (CA2L)	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))

REPLACE ECU OR SENSOR

REPAIR OR REPLACE HARNESS OR CONNECTOR

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