Before you replace the module, check the switch.
This would be the silver push button switch in the door frame.
The switch is open when the door is closed.
This lets the contacts oxidize, and there is no wiping action to clean them.
Unscrew the two screws and pull the switch from the frame.
Use a jumper wire or shaft of a screwdriver and short the two terminals. This should make the steps extend.
You can take the switch apart and clean/lube the contacts.
2014 40QBH Phaeton DP Cummins 380HP ISL, Freightliner XC, 2019 Jeep Grand Cherokee Trailhawk TOAD
Blue Ox Aventa tow bar, SMI Air Force One -Cave Creek, AZ.