Not all of the wire harness, but you would definitely have to rework it some. The only area that concerned me about going anolog was keeping the aux hydraulics buttons functioning.
I was in this position 2 years ago,and was fortunate to stumble on the problem, (loose ground , a screw inside the boss tin box, had to drill out all the rivots to get to it, and tighten the screws a bit) but your symtoms are different. I contemplated going anolog at that time because of the ongoing guage problems I'll get back to this later today, I have some things I need to do right now
I was fortunate that local tech guy had a spare boss tin box. I borrowed it for 100 hours and had no further trouble (original problem was the machine would intermittantly put up gibberish codes on the display and go into warning or shutdown as a result) so I knew the problem was in the box. I unsealed my boss box by drilling out the rivots and took the circuit board to a local electronics shop and ask them to test anything they reconized on the board. He found no problems but re tightened some screws in there because the gibberish “sounded like a bad ground” to him. Which is what bobcat told me too, bad ground somewhere. So clean any ground wire you can find .
Your problem should be a matter of investigating why you have no power on that wire. You would have to ask a tech where that wire is supposed to get power from, but I would trace it back to be sure its not just broke, coroded or somthing. Get a multi meter if you don't have one and test the wire for “continuity” (a continuos circuit)
If you decide the repair is too expensive, or if your really fed up with keeping the boss from beeping at you when it has no just cause. Then anolog is your only route.
I'd be trying to figure out how the aux hydraulics was wired from a tech though. The rest could be acomplished fairly easily. But you would give up you automatic glow plug timer, for a push button and you watch,
You would have to buy a voltmeter, temp guage and sender, and a fuel guage. Measuring the “resistance” in the factory fuel sender, and get a fuel guage that matches the ohms the tank shows at empty and at full with the proper guage. (auto meter and others makes guages for different senders.
The only way I'd pull the factory wire harness was if you had a donor harner from a non boss 753
1, un plug the display and turn on the key and see if it stilled cranked the engine, and
2 see if the fuel shutoff still moved.
3 see if your aux hyd selector button still lights up.
If all these thing still worked then you only need to wire in guages and mount them..
If not you may need to
1 run a power wire from the key to the starter solinoid to make it crank,
2 run a power wire from the key to a relay to enguage the fuel solinoid
3 mount a momentary on switch and run a wire to the glow plug relay
4 figure out how to power up your aux hydraulics.
5 Then mount and connect the guages
All the other boss stuff I'd just leave on the machine, as long as the fuel shut off solinoid is getting power from the key it can't shut you down anyhow, and if there is no display to holler at you, you wont know, problem solved
I had a 93 753 boss and a 2000 773 g (boss type system is std equip on all G series and newer) and both of them have been troublesome to say the least.
Either way, I'd say you'll be a glutton for punishment.