5. FUEL INJECTION SYSTEM MXU 550EXi/MXU500i 2. DTC INSPECTION PROCEDURE Showing four functions on the screen when switching on power. ALC1 is for MXU550EXi AAA5 is for New MXU 500i A). ECU version: Including of model name, ECU number, identifications number and software version. Press the Enter button Press the " Enter " button ALC1 is for MXU550EXi AAA5 is for New MXU 500i 5-32