Toyota Tundra Service Manual: Check Bus 4 Lines for Short Circuit

Toyota Tundra Service Manual / Power Source, Network / Can Communication / 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

*1: for 4WD

*2: w/ Trailer Brake Control System

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)
4 wheel drive control ECU (4WD control ECU)*1
Tire pressure warning ECU and receiver
Airbag sensor assembly
Brake control with bracket relay*2
Spiral with sensor cable sub-assembly (steering angle sensor)
Brake actuator assembly (skid control ECU)
No. 3 CAN junction connector
No. 4 CAN junction connector
No. 6 CAN junction connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

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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Some parts must be initialized and set when replacing or removing and installing parts.
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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 ignition switch to ON and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 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 WIRES (NO. 4 CAN JUNCTION CONNECTOR)

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

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

*a	Front view of wire harness connector (to No. 4 CAN Junction Connector)
*b	to No. 3 CAN Junction Connector
*c	to Spiral with Sensor Cable Sub-assembly (Steering Angle Sensor)
*d	to No. 6 CAN Junction Connector
*e	to Brake Actuator Assembly (Skid Control ECU)

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
J190-8 (CANH) - J190-19 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 3 CAN junction connector
J190-9 (CANH) - J190-20 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Spiral with sensor cable sub-assembly (steering angle sensor)
J190-10 (CANH) - J190-21 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 6 CAN junction connector
J190-11 (CANH) - J190-22 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Brake actuator assembly (skid control ECU)

Result	Proceed to
OK	A
NG (No. 3 CAN junction terminal CAN main wire)	B
NG (No. 6 CAN junction terminal CAN main wire)	C
NG (ECU or sensor CAN branch wire)	D

REPLACE NO. 4 CAN JUNCTION CONNECTOR

GO TO STEP 6

GO TO STEP 10

2.	CONNECT CONNECTOR

(a) Reconnect the J190 No. 4 CAN junction terminal connector.

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

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

*a	Front view of wire harness connector (to No. 3 CAN Junction Connector)
*b	to 4 Wheel Drive Control ECU (4WD Control ECU) (for 4WD)
*c	to No. 4 CAN Junction Connector
*d	to Brake Control with Bracket Relay (w/ Trailer Brake Control System)
*e	to Central Gateway ECU (Network Gateway ECU)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
1: for 4WD 2: w/ Trailer Brake Control System
J188-8 (CANH) - J188-19 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	4 wheel drive control ECU (4WD control ECU)*1
J188-9 (CANH) - J188-20 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 4 CAN junction connector
J188-10 (CANH) - J188-21 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Brake control with bracket relay*2
J188-11 (CANH) - J188-22 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Central gateway ECU (network gateway ECU)

Result	Proceed to
OK	A
NG (Central gateway ECU [network gateway ECU] CAN main wire)	B
NG (No. 4 CAN junction connector CAN main wire)	C
NG (Wire to ECU or sensor)	D

REPLACE NO. 3 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR)

GO TO STEP 10

4.	CONNECT CONNECTOR

(a) Reconnect the J188 No. 3 CAN junction connector.

5.	CHECK FOR OPEN IN CAN BUS WIRE (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 3 CAN JUNCTION CONNECTOR)

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

*a	Front view of wire harness connector (to Central Gateway ECU [Network Gateway ECU])

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
J169-22 (CA2H) - J169-7 (CA2L)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 3 CAN JUNCTION CONNECTOR)

6.	CONNECT CONNECTOR

(a) Reconnect the J190 No. 4 CAN junction terminal connector.

7.	CHECK FOR SHORT IN CAN BUS WIRES (NO. 6 CAN JUNCTION CONNECTOR)

(a) Disconnect the No. 6 CAN junction connector.

*a	Front view of wire harness connector (to No. 6 CAN Junction Connector)
*b	to Tire Pressure Warning ECU and Receiver
*c	to Airbag Sensor Assembly
*d	to No. 4 CAN Junction Connector

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

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
P24-1 (CANH) - P24-12 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Tire pressure warning ECU and receiver
P24-2 (CANH) - P24-13 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Airbag sensor assembly
P24-3 (CANH) - P24-14 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 4 CAN junction connector

Result	Proceed to
OK	A
NG (No. 4 CAN junction connector CAN main wire)	B
NG (Airbag sensor assembly CAN main wire)	C
NG (Wire to ECU or sensor)	D

REPLACE NO. 6 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 6 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR)

GO TO STEP 10

8.	CONNECT CONNECTOR

(a) Reconnect the P24 No. 6 CAN junction connector.

9.	CHECK FOR OPEN IN CAN BUS WIRE (AIRBAG SENSOR ASSEMBLY - NO. 6 CAN JUNCTION CONNECTOR)

(a) Disconnect the airbag sensor assembly connector.

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*a	Front view of wire harness connector (to Airbag Sensor Assembly)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
J177-26 (CANH) - J177-27 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

REPLACE AIRBAG SENSOR ASSEMBLY

REPLACE CAN MAIN WIRE AND CONNECTOR (AIRBAG SENSOR ASSEMBLY - NO. 6 CAN JUNCTION CONNECTOR)

10.	CHECK FOR SHORT IN CAN BUS WIRES (ECU, 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
J169-22 (CA2H) - J169-7 (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

Check Bus 4 Line for Short to GND

Check Bus 5 Line for Short to +B

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