Refer to "51.Engine Control 1A.Troubleshooting(RZ4E-TC) Diagnostic system check-engine controls".
1) Connect the scan tool.
2) Turn OFF the ignition switch for 30 seconds or more.
3) Turn ON the ignition switch.
4) Observe the DTC information with a scan tool. Is a DTC set?
Yes
=>Go to Inspection for short to power supply in ECM main relay power supply circuit.
No
Go to Intermittent conditions of engine.
Refer to "202.Engine 15D.Symptom(RZ4E-TC) intermittent conditions of engine".
1) Turn OFF the ignition switch for 30 seconds or more.
2) Remove the ECM main relay.
3) Turn ON the ignition switch.
4) Observe the DTC information with a scan tool. Is DTC P0685 set?
Yes
=>Go to Inspection for short to power supply in ECM main relay control circuit.
No
Repair the short to the battery power supply in the battery power supply circuit between the ECM (pins 2 and 5 of C7) and the ECM main relay (pin 2 of the Fuse and Relay Box (Engine Compartment) ECM MAIN).
1) Turn OFF the ignition switch for 30 seconds or more.
2) Replace the ECM main relay with a known good relay.
3) Turn ON the ignition switch.
4) Observe the DTC information with a scan tool. Is a DTC set?
Yes
Repair the short to the battery power supply in the control circuit between the ECM (pins 21 and 40 of C7) and the ECM main relay (pin 3 of the Fuse and Relay Box (Engine Compartment) ECM MAIN).
No
Replace the ECM main relay.
1) Clear the DTC with a scan tool.
2) Turn OFF the ignition switch for 30 seconds or more.
3) Turn ON the ignition switch.
4) Observe the DTC information with a scan tool.