As our beloved vans only get older, cracked and frayed wiring becomes more and more common. A good mechanic will recognize this and take the extra time to check the wiring before just throwing parts at a problem.
The area where the wiring harness passes behind the fuel filter is a common spot for wiring issues.
This particular broken wire was found at the turbo actuator. A non Sprinter mechanic would have plugged in their diagnostic machine, followed the flow chart, cross referenced the part numbers and delivered the message to you that a $2000 new turbo was needed!
I hear horror stories about this stuff every day.
Some mechanics are honest but ill informed. Others are down right crooks. Either way, you are paying the bill.
Be careful out there guys!