@deckingman It appears there's a bug or change in Simplify3d. If you state the bed temps it then follows it with two identical lines with -1 as the target temperature!! I think that's why the M116 was there to circumvent that behaviour. It puts M104 followed by M109 as defaults, maybe for compatability with Marlin as well. In the end this is the script that works without M140 or M190 defined at all. It puts the bed heater values in the correct place in the Gcode file just prior to the script entries.
G21 ;metric values
G90 ;absolute positioning
G1 X0 Y0 Z15 F3000
M104 S[extruder0_temperature] ;Start heating extruder
M109 S[extruder0_temperature] ;Wait for extruder to reach temp before proceeding