DTC U0129[00] Lost Communication With Brake System Control Module (Information Module)

1. Information module system check

Refer to "64.Body Control 10I.Troubleshooting(Information Module) diagnostic system check - information module".

2. Programming verification

1) Connect the scan tool.

2) Display the Vehicle Configuration All Data Setting / Change on the scan tool and verify that the equipped ECU information is programmed correctly.

3) If it is not programmed correctly, reprogram the correct value.

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control information module setting".

Procedure completion

=>Go to Current DTC check.

3. Current DTC check

1) Turn OFF the ignition switch.

2) Turn ON the ignition switch and wait for 5 seconds or more.

3) Observe the DTC information with a scan tool. Is a DTC set?

Yes

=>Go to EHCU communication verification.

Go to Intermittent conditions of information module.

Refer to "223.Body Control 36D.Symptom(Information Module) Intermittent Conditions of Information Module".

4. EHCU communication verification

1) Verify communication with the EHCU using the scan tool. Can communication with the EHCU be established?

Yes

=>Go to EHCU DTC check.

No (Models with radar sensors/stereo cameras)

Go to Lost communication with the EHCU.

Refer to "54.Brake Control 4A.Troubleshooting(ABS/ESC) lost communication with the EHCU (models with radar sensor/ stereo camera)".

No (Models without radar sensors and stereo cameras)

Go to Lost communication with the EHCU.

Refer to "54.Brake Control 4A.Troubleshooting(ABS/ESC) lost communication with the EHCU (models without radar sensor and stereo camera)".

5. EHCU DTC check

1) Observe the EHCU DTC information with a scan tool. Is an EHCU DTC set?

Yes

Go to the applicable DTC diagnosis.

=>Go to CAN communication circuit inspection.

6. CAN communication circuit inspection

1) Inspect the CAN Low circuit and CAN High circuit between the information module (pins 11 and 23 of C105) and the EHCU (pins 14 and 26 of C13) for the following. Is the result normal?

Open circuit or high resistance
Short together between circuits
Short to battery or short to ignition power supply circuit
Short to ground

Refer to "LHD Controller Area Network (Central Gateway C/U)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Controller Area Network (Except Central Gateway C/U)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Controller Area Network (Central Gateway C/U (4JJ3 with DPD))" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Controller Area Network (Central Gateway C/U (4JJ3 without DPD, RZ4E))" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to EHCU harness connector inspection.

Repair the circuit as necessary.

=>Go to Repair verification.

7. EHCU harness connector inspection

1) Inspect for poor connections at the EHCU harness connector (pins 14 and 26 of C13). Is the connection status normal?

Refer to "LHD Controller Area Network (Central Gateway C/U)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Controller Area Network (Except Central Gateway C/U)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Controller Area Network (Central Gateway C/U (4JJ3 with DPD))" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Controller Area Network (Central Gateway C/U (4JJ3 without DPD, RZ4E))" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to Information module harness connector inspection.

Repair the connections as necessary.

=>Go to Repair verification.

8. Information module harness connector inspection

1) Inspect for poor connections at the information module harness connector (pins 11 and 23 of C105). Is the connection status normal?

Refer to "LHD Controller Area Network (Central Gateway C/U)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "LHD Controller Area Network (Except Central Gateway C/U)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Controller Area Network (Central Gateway C/U (4JJ3 with DPD))" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Controller Area Network (Central Gateway C/U (4JJ3 without DPD, RZ4E))" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

Replace the EHCU.

Note

Perform programming after replacing the EHCU.

Refer to "4.Brakes 4Z.Brake Electrical Control EHCU removal".

Refer to "4.Brakes 4Z.Brake Electrical Control EHCU installation".

Refer to "4.Brakes 4Z.Brake Electrical Control EHCU setting".

=>Go to Current DTC follow-up check.

Repair the connections as necessary.

=>Go to Repair verification.

9. Current DTC follow-up check

1) Turn OFF the ignition switch for 30 seconds or more.

2) Turn ON the ignition switch and wait for 5 seconds or more.

3) Observe the DTC information with a scan tool. Is a DTC set?

Yes

=>Go to Information module replacement.

=>Go to Repair verification.

10. Information module replacement

Note

After replacing the information module, programming must be performed.

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control information module removal".

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control information module installation".

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control information module setting".

Procedure completion

=>Go to Repair verification.

11. Repair verification

1) Turn OFF the ignition switch for 30 seconds or more.

2) Turn ON the ignition switch and wait for 5 seconds or more.

3) Observe the DTC information with a scan tool.