Toyota Tundra 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 there is no resistance 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.

Symptom

Trouble Area

There is no resistance 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 bus line
  • Central gateway ECU (network gateway ECU)
  • ECM

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.

    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

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 WIRE (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU])

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

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

*a

Front view of wire harness connector

(to Central Gateway ECU [Network Gateway ECU])

*b

Front view of DLC3

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J169-18 (CA4H) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

J169-17 (CA4L) - J17-16 (BAT)

OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

2.

CHECK FOR SHORT TO B+ IN CAN BUS WIRE (ECM)

(a) Disconnect the ECM junction connector.

*A

for 1UR-FE

*B

for 3UR-FE, 3UR-FBE

*a

Front view of wire harness connector

(to ECM)

*b

Front view of DLC3

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

Standard Resistance:

for 1UR-FE

Tester Connection

Condition

Specified Condition

A24-10 (CANH) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

A24-11 (CANL) - J17-16 (BAT)

for 3UR-FE, 3UR-FBE

Tester Connection

Condition

Specified Condition

A24-11 (CANH) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

A24-19 (CANL) - J17-16 (BAT)

OK

REPLACE ECM

NG

REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (ECM - CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU])

    Check Bus 1 Lines for Short Circuit

    Check Bus 2 Line for Short to GND

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