Toyota Tundra Service Manual: Open in Bus 3 Main Bus Line

DESCRIPTION

There may be an open circuit in one of the CAN main bus lines when the resistance between terminals 6 (CA3H) and 21 (CA3L) or 19 (CAYH) and 20 (CAYL) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.

This malfunction is not related to the lines of a CAN branch or to ECUs or sensors connected to a CAN branch.

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

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

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

*a Front view of wire harness connector (to No. 5 CAN Junction Connector) *b to Central Gateway ECU (Network Gateway ECU) (CA3H and CA3L Terminal) *c to Central Gateway ECU (Network Gateway ECU) (CAYH and CAYL Terminal)

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

Standard Resistance:

OK

REPLACE NO. 5 CAN JUNCTION CONNECTOR

NG

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

*a Front view of wire harness connector (to Central Gateway ECU [Network Gateway ECU])

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

Standard Resistance:

OK

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

NG

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)