Dear Group Sometimes, I just can't arm the A/T switch on the MCP.I got red blinking warning A/T P/RST instead. Any possible cause ?Thanks in advance.

"Sometimes, I just can't arm the A/T switch on the MCP.I got red blinking warning A/T P/RST instead. Any possible cause ?"A possible solution to this might be to apply electrical power to the main electrical busses (By switching on Ext Power, APU power or Engine Generator power). If in doubt as to how to apply power, please read the tuturials, checklists and PMDG-supplied manuals or use the helpful Advanced Search function for this forum.The latch mechanism for the switch requires power from the Main DC Busses (Left or Right). Battery power is not sufficient.CheersIan.