There should be two hoses which attach to this tank. Find the one that's disconnected... that's where it'll reattach. How... that depends. If it's just a clamp which came off, you go to NAPA or wherever, and buy a hose clamp... get the ones that you tighten down with a screwdriver or an 8mm or 5/16" socket... don't get the self tightening ones which you just use a pair of pliers for.. those are junk. If the piece which the hose attaches to came off the reservoir tank, you'll have to replace the reservoir tank.
A '96 jimmy does not have a body control module (bcm), it does, however, have an engine control module (ecm) located ontop of the coolant reservoir.
gmc jimmy rear reservoir location
Low engine coolant or ineffective coolant. Add or replace anti freeze
Power Steering pump reservoir.
Dex-cool coolant highly corrosive is eating away at gaskets mainly intake manifold gasket.
Check the brake fluid level in the reservoir, if it is low you have a leak somewhere.
There is a turn plug on the rightside of the bottom of a radiator turn it and it will drain.
bad water pump or thermostat. check both.
water temperature sensor located near steering colum..
Low coolant? Heater control cable not adjusted properly? Bad thermostat? Heater core "airbound"? Water pump not circulating coolant?
Coolant temp sensors are usually located very close to the thermostat housing, so follow the upper radiator hose to the engine, it will attach to the thermostst housing and you will see the coolant sensor close by.
It is located right on the windshield washer reservoir. It looks like a short black cylinder.