Toyota Tundra Service Manual: Check Bus 2 Lines for Short Circuit

Toyota Tundra Service Manual / Power Source, Network / Can Communication / Can Communication System / Check Bus 2 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the CAN main bus lines when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom	Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.	Short in CAN main bus lines 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 IN CAN BUS WIRES (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - ECM)

(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])

Standard Resistance:

Tester Connection	Condition	Specified Condition
J169-18 (CA4H) - J169-17 (CA4L)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

2.	CONNECT CONNECTOR

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

3.	CHECK FOR SHORT IN CAN BUS WIRES (ECM - CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU])

(a) Disconnect the ECM connector.

for 1UR-FE

for 3UR-FE, 3UR-FBE

Front view of wire harness connector

(to ECM)

(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) - A24-11 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

for 3UR-FE, 3UR-FBE

Tester Connection	Condition	Specified Condition
A24-11 (CANH) - A24-19 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

REPLACE ECM

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

Check Bus 2 Line for Short to GND

Check Bus 3 Line for Short to +B

See More:

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