It takes 2 failures to get a "hot frame"
If there is only a short to the frame (say the hot wire on your jack is touching the frame; AND the frame is properly safety grounded) it will blow the fuse or trip the breaker.
If there is only an open ground, nothing will happen at all and you would never know unless you tested it by using an ohm meter from the frame to a good earth ground (like a wet spot in the dirt) or with a GFCI outlet tester (when button pressed it switches from "GOOD" to "OPEN GROUND" and the GFCI does not switch off).
It IS possible that you could still have a high impedance connection through one of your induction motors - AC fan or compressor - and get enough for a "tickle" in this case; however the open ground is still a requirement.
So, a bad safety ground AND a short to safety ground (frame) is needed for the frame to be at a higher voltage than the dirt (concrete).
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW