Refer to "56.Steering Control 6A.Troubleshooting diagnostic system check-electric power steering controls".
1) Connect the scan tool.
2) Start the engine.
3) Observe the DTC information with a scan tool. Is a DTC set?
Yes
=>Go to EHCU communication verification.
No
Go to Intermittent conditions of electric power steering control system.
Refer to "207.Steering 20D.Symptom intermittent conditions of electric power steering control system".
1) Use the scan tool to communicate with the EHCU and display the data. Can communication with the EHCU be established?
Yes
No
Go to Lost communication with the EHCU.
1) Observe the EHCU DTC information with a scan tool. Is a DTC set?
Yes
Go to the applicable DTC diagnosis.
No
=>Go to Chassis CAN communication circuit inspection.
1) Inspect the CAN Low circuit and CAN High circuit between the EPS motor control unit (pins 4 and 5 of C116) and the EHCU (pins 14 and 26 of C13) for the following. Is the result normal?
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.
No
Repair the circuit as necessary.
1) Inspect for poor connections at the EHCU harness connector (pins 14 and 26 of C13). Is the connection status normal?
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 EPS motor control unit harness connector inspection.
No
Repair the connections as necessary.
1) Inspect for poor connections at the EPS motor control unit harness connector (pins 4 and 5 of C116). Is the connection status normal?
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
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.
No
Repair the connections as necessary.
1) Securely connect the disconnected harness connectors.
2) Clear the DTC with a scan tool.
3) Turn OFF the ignition switch for 30 seconds or more.
4) Turn ON the ignition switch.
5) Observe the DTC information with a scan tool. Is a DTC set?
Yes
=>Go to EPS motor control unit replacement.
No
Note
Refer to "6.Steering 6B.Power Assisted System power steering unit removal".
Refer to "6.Steering 6B.Power Assisted System power steering unit disassembly".
Refer to "6.Steering 6B.Power Assisted System power steering unit reassembly".
Refer to "6.Steering 6B.Power Assisted System power steering unit installation".
Refer to "6.Steering 6B.Power Assisted System power steering unit setting".
Procedure completion
1) Securely connect the disconnected harness connectors.
2) Clear the DTC with a scan tool.
3) Turn OFF the ignition switch for 30 seconds or more.
4) Turn ON the ignition switch.
5) Observe the DTC information with a scan tool.