In answering the question ( posted in the title of the thread) to myself, I found the quick and definitive way to answer it was to rephrase it this way " Would you risk termination by operating unsafe equipment?" . By doing that , I put both "risking termination" and "operating unsafe equipment" on the same side of the ledger where they belong, in my opinion. If by operating that unsafe equipment, it puts you in a position of having your job taken away from you as a result of the actions due to the unsafe equipment, i.e an accident, then I think it is a no brainer. Refuse to drive that vehicle unless it is fixed or replaced with another one.
I suppose it is easier for a tractor to be swapped out for another than it is for a package car that is already loaded so maybe that option of swapping out is more readily accepted in feeders than it would be for the package delivery side of operations.
That much being said, be a little creative, carry with you extra bulbs(the mechanics generally are happy to supply you with them, emphasis on "generally"). A marker light being out ain't a big deal but a turn signal that doesn't work can result in an accident and a ticket for "failure to signal" which places the blame on you as a driver. If the problem can be fixed with a new bulb, great. If you can trace the wire and find the break , great. If not, then don't drive and if you do(free will), be sure you are aware of the consequences that can result from the equipment that is defective.
That's all I gotta say for the time being.