This bulletin applies to 2015 Infiniti Q50/Q60, 2015-2019 Q70, 2015-2017 QX50, 2015 QX60 and 2015-2017 QX70 vehicles. The MIL may be on, with DTC P0603 (ECM back up/circuit).
Confirm that the battery voltage is 11 volts or more with the ignition on/engine off. Erase the DTC. Perform DTC confirmation steps in the service procedure. Confirm that the first trip DTC P0603 is not stored. This DTC is often the result of a low battery voltage, a discharged battery or battery terminal disconnections.
Service procedure:
Confirm that the battery voltage is at least 11 volts with the ignition on.
Connect the C-II plus VI to the vehicle.
Open C-II plus on the Consult PC.
Turn the ignition on but do not start the engine.
Erase the DTC.
Turn the ignition off.
Turn the ignition on and wait for at least 1 second.
Turn the ignition off and wait for at least 10 seconds.
Repeat Steps 7 and 8 ten times and then go to Step 10.
Turn the ignition on. If DTC P0603 is not currently stored as a first trip DTC, the procedure is done. If the DTC remains, refer to the service manual for further diagnostics.
About the Author
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Mike Mavrigian
Motor Age Editor
Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.