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Toyota Tacoma (2015-2018) Service Manual / Can Communication / Can Communication System / Check Bus 2 Line for Short to +B

Toyota Tacoma (2015-2018) Service Manual: Check Bus 2 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 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Detection Item

Trouble Area

No resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.
  • Short to +B in CAN main lines
  • Short to +B 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 / 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.

    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

  • Some parts must be initialized and set when replacing or removing and installing parts.

    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 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.

    Click here

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

    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 B+ IN CAN BUS LINE (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

*1

DLC3

-

-

*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)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

J16-1 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Brake booster assembly (skid control ECU)*1 or brake actuator assembly (skid control ECU)*2

J16-11 (CANL) - D4-16 (BAT)

J16-2 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

No. 2 CAN junction connector

J16-12 (CANL) - D4-16 (BAT)

J16-3 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Air conditioning amplifier assembly

J16-13 (CANL) - D4-16 (BAT)

J16-5 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

ECM

J16-15 (CANL) - D4-16 (BAT)

J16-6 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Central gateway ECU (network gateway ECU)

J16-16 (CANL) - D4-16 (BAT)

J16-7 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Airbag sensor assembly

J16-17 (CANL) - D4-16 (BAT)

J16-8 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

4 wheel drive control ECU*3

J16-18 (CANL) - D4-16 (BAT)
  • *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
A

REPLACE NO. 1 CAN JUNCTION CONNECTOR
B

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

GO TO STEP 3

E

GO TO STEP 4

C

2.

CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

(a) Disconnect the N36 central gateway ECU (network gateway ECU) connector.

Text in Illustration

*1

DLC3

-

-

*a

Front view of wire harness connector

(to No. 1 CAN Junction Connector)

*b

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

J16-6 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

J16-16 (CANL) - D4-16 (BAT)
OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

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

3.

CHECK FOR SHORT TO B+ IN CAN BUS LINE (NO. 2 CAN JUNCTION CONNECTOR)

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

Text in Illustration

*1

DLC3

-

-

*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

-

-

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

J3-1 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

No. 1 CAN junction connector

J3-11 (CANL) - D4-16 (BAT)

J3-2 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Door control and tire pressure monitoring system receiver assembly*1

J3-12 (CANL) - D4-16 (BAT)

J3-4 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Main body ECU (multiplex network body ECU)

J3-14 (CANL) - D4-16 (BAT)

J3-5 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Certification ECU (smart key ECU assembly)*2

J3-15 (CANL) - D4-16 (BAT)

J3-6 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Combination meter assembly

J3-16 (CANL) - D4-16 (BAT)

J3-7 (CANH) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Spiral cable with sensor sub-assembly

J3-17 (CANL) - D4-16 (BAT)
  • *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
A

REPLACE NO. 2 CAN JUNCTION CONNECTOR
B

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

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

4.

CHECK FOR SHORT TO B+ 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 bus line shorted to +B is connected

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

N36-18 (CA4H) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

N36-17 (CA4L) - D4-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher
Text in Illustration

*a

Component with harness connected

(Central Gateway ECU (Network Gateway ECU))

*b

Front view of DLC3

HINT:

If the resistance changes to 6 kΩ or higher when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.

OK

REPLACE ECU OR SENSOR
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
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