ECM Backup Circuit DTC
This bulletin applies to 2015 and later Infiniti vehicles. The MIL may be on, with DTC P0603 stored (ECM Back Up/Circuit).
Confirm that the battery voltage is 11 volts or more with the ignition on, engine off. This DTC is often the result of low battery voltage, a discharged battery or battery terminal disconnections.
Resolve any low battery conditions before proceeding.
1. Resolve any low battery conditions before proceeding (battery should show 11 volts or more and battery cables are clean and tight).
2. Connect C-III plus VI to the vehicle.
3. Open C-III plus on the CONSULT PC.
4. Turn the ignition on, with engine off.
5. Erase DTCs.
6. Turn the ignition off.
7. Tum the ignition on and wait for at least 1 second.
8. Turn the ignition off and wait for at least 10 seconds.
9. Repeat steps 7 and 8 ten times, and then proceed to Step 10.
10. Turn the ignition on.
11. Is P0603 currently stored as a 1st trip DTC? If no, the service procedure is complete. If yes, refer to the Electronic Service Manual (ESM), section EC – Engine Control System for further diagnostic information.