Why is the AWD front differential 'venting' fluid out of the vent tube?

You have an all wheel disabled message because there is an error in the system.

It should only come out if there is wayyy too much fluid in there, it has water in it, or the car went upside down. If it is a front wheel drive car with the diff built in, then i would say there is a leak in the output shaft seal causing trans fluid to go into the diff, and i would say check the trans fluid. There should be a cap on the hose for the vent, but justto keep dust out and let air pass

the differential action means that the wheel with the least resistance will spin faster than the other. The other turn because of friction and fluid motion. Should you grab hold of the turning wheel then the other wheel will pick up speed and spin. The differential has nothing to do with stalling and engine performance problems
Run the fault codes and check for vacuum leaks especially in the vent controls under the dash and brake booster

IF you are in constant 4wd then you will not have a centre diff unless you have an AWD. The difference is that AWD transfer cases have a centre diff that allows different road speeds between the front and rear diffs as in going over speed bumps and dips ion the road It is the same operation in the front and rear diffs that allow one wheel to go faster than the other when cornering. However in 4wd drive there is no diff action in the transfer case and both front and rear axles drive at the same speed regardless of speed bumps and dips in the road . This action produces what is known as torque wind up which results in the handling characteristics. This torque wind up places stress on all the drive line train and results in failures such as .that you describe.. This wind up is not noticeable when driving on loose surfaces slippery surfaces or in mud as it is allowed to escape when the wheels spin . If you have an AWD with diff lock capabilities then check that the diff lock is operating correctly

The water in the front differential is caused by driving through high water. There is a vent at the top that allows for the expansion of oil without building up air pressure. You are going to need to replace the front fluid and repack the bearings to prevent further damage. It is also recommended to install a vent tube to prevent it from happening again.

If you need further help, reach me via phone at https://www.6ya.com/expert/scott_843b43f7ebebd3f5

The tube you mention is probably the "vent" for the differential. Since the differential is low on the vehicle, water and dirt are concerns. By moving the vent to a higher location, problems with dirt and water are reduced.

Its called a vent tube, its not supposed to hook to anything, it is serving its purpose just hanging there.

2000 GMC TRUCKS SSERIES JIMMY 4.3L 6-cyl Engine Code [W]
Differential, Front......GL-5 All TEMPS......80W-90 Manufacturer recommends GM part no. 1052271 or equivalent Do not add limited slip additive.
Differential, With 7.25 RingGear Front..........1.2 liters
Differential, With 8.25 RingGear Front..........2 liters
Differential, With 9.25 RingGear Front..........2.8 liters

2000 TOYOTA TACOMA 2.7L 4-cyl Engine Code 3RZ-FE

Engine Oil Grade 1......API* All TEMPS......5W-30 Optional ..10W-30
Engine, 2WD, with filter..........5.5 liters
Engine, 4WD, with filter..........5.4 liters

Manual Transmission,......GL-5/ GL-4 All TEMPS......75W-90
Automatic Transmission,A340E......AF3 / A43D......AF3

Differential, Front/ Rear W/ ADRD......GL-5 ALL TEMPS......75W-90
Differential, Front Less ADRD......GL-5 ALL TEMPS......80W-90

Transfer Case,......GL-4/GL-5 ALL TEMPS......75W-90 Gear oil.

Capacity:
Cooling System, Initial Fill..........8.5 liters
Automatic Transmission, A340E Initial Fill..........1.6 liters
Automatic Transmission, A340F Initial Fill..........2 liters
Automatic Transmission, A43D Initial Fill..........2.4 liters
Automatic Transmission, Total Fill
4 speed A340E..........7.2 liters
4 speed A340F..........10.1 liters
4 speed A43D..........6.5 liters
Manual Transmission, ..........2.5 liters
Differential, With ADRD Front..........1.2 liters
Differential, Without ADRD Front..........1.1 liters
Differential, 2WD V6 Rear..........2.6 liters
Differential, 4WD Extra Long Rear..........2.5 liters
Differential, Short WB With LSD Rear..........2.7 liters
Differential, Short WB Without LS Rear..........2.6 liters
Transfer Case, Electronic..........1.2 liters
Transfer Case, STD..........1 liters

5.7 liter V8 Engine code 2: Fluid capasity: Engine oil with filter 6.6 liter 5W-20,  Cooling system: Total fill 13.7 liter Automatic transmission total fill 13.3 liter Front differential 1.7 liter Rear differential 2.23 liter Transfercase 1.8 liter
4.7 liter Engine code N Fluid capasity: Engine oil with filter 5.7 liter 5W-30 Cooling system: Total fill 13.7 liter Automatic transmission total fill 13.3 liter Front differential 1.7 liter Rear differential 2.2 liter Transfer case 1.7 liter
3.7 liter Engine code K Fluid Capasity: Engine oil with filter 4.7 liter 5W-30 Cooling system: Total fill 10.0 liter Automatic transmission total fill 13.3 liter (W5A580 7.7 liter) Front differential 1.7 liter Rear differential 2.2 liter Transfer case 1.7 liter.
Hope this helps, and good luck.