Toyota Tundra Service Manual: Check Bus 2 Line for Short to GND

Toyota Tundra Service Manual / Power Source, Network / Can Communication / Can Communication System / Check Bus 2 Line for Short to GND

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and GND when there is no resistance between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom

Trouble Area

There is no resistance between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.
  • Short to GND 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.

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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 TO GND 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) - J17-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

J169-17 (CA4L) - J17-4 (CG)
OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

2.

CHECK FOR SHORT TO GND 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) - J17-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

A24-11 (CANL) - J17-4 (CG)
for 3UR-FE, 3UR-FBE

Tester Connection

Condition

Specified Condition

A24-11 (CANH) - J17-4 (CG)

Cable disconnected from negative (-) battery terminal

200 Ω or higher

A24-19 (CANL) - J17-4 (CG)
OK

REPLACE ECM

NG

REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (ECM - CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU])
    Check Bus 2 Line for Short to +B

    Check Bus 2 Lines for Short Circuit

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