On the new model trucks comming out now generally the deadman switch is wired so that it has to activate a line (power) contactor to energize the system before anything will work.
On the older trucks they weren't wired in this way and the hydraulics would work even if you were off the truck.
It has become apparent to me they have done this as a safety measure to keep any system from working while the operator is not on the truck.
So to answer your question about making the hydraulics work without depressing the deadman? i'm sure its possible but would you want to bypass a "safety feature" on the truck?
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