Toyota Tundra Service Manual: Check Bus 3 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus wires and +B when no resistance exists between terminal 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 21 (CA3L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 19 (CAYH) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 20 (CAYL) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Symptom

Trouble Area

*1: w/ Audio and Visual System

*2: w/ Navigation System

  • No resistance exists between terminal 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 21 (CA3L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.
  • No resistance exists between terminal 19 (CAYH) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 20 (CAYL) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.
  • Short to +B in CAN main bus line
  • Short to +B in CAN branch line
  • Central gateway ECU (network gateway ECU)
  • Radio and display receiver assembly*1
  • Navigation receiver assembly*2
  • No. 5 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.

    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] - NO. 5 CAN JUNCTION CONNECTOR)

(a) Disconnect the cable from 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

J169-6 (CA3H) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

J169-21 (CA3L) - J17-16 (BAT)

J169-19 (CAYH) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

J169-20 (CAYL) - J17-16 (BAT)

OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

2.

CONNECT CONNECTOR

(a) Reconnect the J169 central gateway ECU (network gateway ECU) connector.

NEXT

3.

CHECK FOR SHORT TO +B IN CAN BUS WIRE (NO. 5 CAN JUNCTION CONNECTOR)

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

*a

Front view of wire harness connector

(to No. 5 CAN Junction Connector)

*b

Front view of DLC3

*c

  • to Navigation Receiver Assembly (w/ Navigation System)
  • to Radio and Display Receiver Assembly (w/ Audio and Visual System)

*d

to Central Gateway ECU (Network Gateway ECU) (CA3H and CA3L Terminal)

*e

to Central Gateway ECU (Network Gateway ECU) (CAYH and CAYL Terminal)

-

-

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

*1: w/ Navigation System

*2: w/ Audio and Visual System

J189-9 (CANH) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

  • Navigation receiver assembly*1
  • Radio and display receiver assembly*2

J189-20 (CANL) - J17-16 (BAT)

J189-10 (CANH) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Central gateway ECU (network gateway ECU) (CA3H and CA3L terminal)

J189-21 (CANL) - J17-16 (BAT)

J189-11 (CANH) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

Central gateway ECU (network gateway ECU) (CAYH and CAYL terminal)

J189-22 (CANL) - J17-16 (BAT)

Result

Proceed to

OK

A

NG (Central gateway ECU [network gateway ECU] CAN main wire)

B

NG (ECU or sensor CAN branch wire)

C

A

REPLACE NO. 5 CAN JUNCTION CONNECTOR

B

REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 5 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU])

C

4.

CHECK FOR SHORT TO +B IN CAN BUS WIRE (ECU, SENSOR)

(a) Reconnect all wire harness connectors.

*a

Component with harness connected

(Central Gateway ECU [Network Gateway ECU])

*b

Front view of DLC3

(b) Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short to +B is connected.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J169-6 (CA3H) - J17-16 (BAT)

Cable disconnected from negative (-) battery terminal

6 kΩ or higher

J169-21 (CA3L) - J17-16 (BAT)

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.
  • If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short to +B in the wire harness and repair or replace the wire harness or connector if necessary.
OK

REPLACE ECU OR SENSOR

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

    Check Bus 2 Lines for Short Circuit

    Check Bus 3 Line for Short to GND

    See More:

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