this part sounds scary. maybe we wont be able to load MM on it after the update?
Secure Bootloader software
If the Engine Control Module (ECM) does not have a calibration installed, or has an
unapproved calibration installed then the ECM will be in a Read Only Memory (ROM) boot
state. The ECM will have power but the lack of approved software will not allow the vehicle
to be started and driven. No further diagnostics of the ECM will be available at this time.
This code will be cleared and issue resolved when the ECM is updated with the correct
approved calibration. Refer to the DealerCONNECT > TechCONNECT > Service
Information for more detail.
DTC U1601 set outside of the dealership with a no crank (towed in), no start condition
caused by unauthorized (up-rate) software will NOT be covered under the terms of the
DTC U1601 code may also be set when a legitimate flash is interrupted for any reason.