Toyota Tacoma (2015-2018) Service Manual: Check Bus 2 Lines for Short Circuit

Toyota Tacoma (2015-2018) Service Manual / Can Communication / Can Communication System / Check Bus 2 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 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Detection Item	Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of central gateway ECU (network gateway ECU) is below 54 Ω.	Short in CAN main lines Short in CAN branch lines Central gateway ECU (network gateway ECU) ECM Main body ECU (multiplex network body ECU) Air conditioning amplifier assembly Airbag sensor assembly Spiral cable with sensor sub-assembly Combination meter assembly Certification ECU (smart key ECU assembly)1 4 wheel drive control ECU2 Door control and tire pressure monitoring system receiver assembly3 Brake booster assembly (skid control ECU)4 Brake actuator assembly (skid control ECU)*5 No. 1 CAN junction connector No. 2 CAN junction connector

Detection Item

Trouble Area

Resistance between terminals 18 (CA4H) and 17 (CA4L) of central gateway ECU (network gateway ECU) is below 54 Ω.

Short in CAN main lines
Short in CAN branch lines
Central gateway ECU (network gateway ECU)
ECM
Main body ECU (multiplex network body ECU)
Air conditioning amplifier assembly
Airbag sensor assembly
Spiral cable with sensor sub-assembly
Combination meter assembly
Certification ECU (smart key ECU assembly)*1
4 wheel drive control ECU*2
Door control and tire pressure monitoring system receiver assembly*3
Brake booster assembly (skid control ECU)*4
Brake actuator assembly (skid control ECU)*5
No. 1 CAN junction connector
No. 2 CAN junction connector

*1: w/ Smart Key System
*2: for 4WD
*3: w/ Tire Pressure Warning System and Tire Inflation Pressure Display Function
*4: for Hydraulic Brake Booster
*5: for Vacuum Brake Booster

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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If the main body ECU (multiplex network body ECU) or certification ECU (smart key ECU assembly) is replaced, refer to Registration.
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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. 1 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the No. 1 CAN junction connector.

Text in Illustration

*a	Front view of wire harness connector (to No. 1 CAN Junction Connector)	*b	to Brake Booster Assembly (Skid Control ECU) (for Hydraulic Brake Booster) or Brake Actuator Assembly (Skid Control ECU) (for Vacuum Brake Booster)
*c	to No. 2 CAN Junction Connector	*d	to Air Conditioning Amplifier Assembly
*e	to ECM	*f	to Central Gateway ECU (Network Gateway ECU)
*g	to Airbag Sensor Assembly	*h	to 4 Wheel Drive Control ECU (for 4WD)

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
J16-1 (CANH) - J16-11 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Brake booster assembly (skid control ECU)1 or brake actuator assembly (skid control ECU)2
J16-2 (CANH) - J16-12 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 2 CAN junction connector
J16-3 (CANH) - J16-13 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Air conditioning amplifier assembly
J16-5 (CANH) - J16-15 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	ECM
J16-6 (CANH) - J16-16 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Central gateway ECU (network gateway ECU)
J16-7 (CANH) - J16-17 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Airbag sensor assembly
J16-8 (CANH) - J16-18 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	4 wheel drive control ECU*3

*1: for Hydraulic Brake Booster
*2: for Vacuum Brake Booster
*3: for 4WD

Result

Result	Proceed to
OK	A
NG (ECM CAN main line)	B
NG (Central gateway ECU (network gateway ECU) CAN branch line)	C
NG (No. 2 CAN junction connector CAN main line)	D
NG (ECU or sensor CAN branch lines)	E

REPLACE NO. 1 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN LINE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - ECM)

GO TO STEP 3

GO TO STEP 4

2.	CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

(a) Disconnect the N36 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
J16-6 (CANH) - J16-16 (CANL)	Cable disconnected from negative (-) battery terminal	1 MΩ or higher

Text in Illustration

Front view of wire harness connector

(to No. 1 CAN Junction Connector)

to Central Gateway ECU (Network Gateway ECU)

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

3.	CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)

(a) Reconnect the J16 No. 1 CAN Junction Connector.

(b) Disconnect the No. 2 CAN junction connector.

Text in Illustration

*a	Front view of wire harness connector (to No. 2 CAN Junction Connector)	*b	to No. 1 CAN Junction Connector
*c	to Door Control and Tire Pressure Monitoring System Receiver Assembly (w/ Tire Pressure Warning System and Tire Inflation Pressure Display Function)	*d	to Main Body ECU (Multiplex Network Body ECU)
*e	to Certification ECU (Smart Key ECU Assembly) (w/ Smart Key System)	*f	to Combination Meter Assembly
*g	to Spiral Cable with Sensor Sub-assembly	-	-

Standard Resistance:

Tester Connection	Condition	Specified Condition	Connected to
J3-1 (CANH) - J3-11 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 1 CAN junction connector
J3-2 (CANH) - J3-12 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Door control and tire pressure monitoring system receiver assembly*1
J3-4 (CANH) - J3-14 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Main body ECU (multiplex network body ECU)
J3-5 (CANH) - J3-15 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Certification ECU (smart key ECU assembly)*2
J3-6 (CANH) - J3-16 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Combination meter assembly
J3-7 (CANH) - J3-17 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Spiral cable with sensor sub-assembly

*1: w/ Tire Pressure Warning System and Tire Inflation Pressure Display Function
*2: w/ Smart Key System

Result

Result	Proceed to
OK	A
NG (Combination meter assembly CAN main line)	B
NG (No. 1 CAN junction connector CAN main line)	C
NG (ECU or sensor CAN branch lines)	D

REPLACE NO. 2 CAN JUNCTION CONNECTOR

REPAIR OR REPLACE CAN MAIN LINE OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - COMBINATION METER ASSEMBLY)

REPAIR OR REPLACE CAN MAIN LINE OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR)

4.	CHECK FOR SHORT IN CAN BUS LINES (ECU, SENSOR)

(a) Reconnect the CAN junction connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
N36-18 (CA4H) - N36-17 (CA4L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Text in Illustration

*a	Component with harness connected (Central Gateway ECU (Network Gateway ECU))

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.

REPLACE ECU OR SENSOR

REPAIR OR REPLACE HARNESS OR CONNECTOR

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