My transfer case engages the front driveshaft but not the front differential thanks dave

The actuator will not be on the front differential or drive line, it will be on the transfer case, which is mounted behind the transmission. Follow the front drive shaft back from the front differential, and the component at the rear of the driveshaft is the transfer case. That is where four wheel drive is engaged/disengaged.
I'm not familiar with your vehicle, but if you have a separate lever to engage 4wd, there will not be a fuse for the actuator - it is a manual system. If the 4wd is selected electrically, check that all wiring and connectors on the transfer case are in good condition.

Depends on what sort of set up you have.

If there's a transfer case - it's like another gearbox on the transmission - it's the transfer case (I.e a gearbox..) that supplies power to your front wheels.

The transfer case is itself powered by the transmission. You will have a propshaft (driveshaft) running from the transfer case to the front differential.

2 speed electric shift transfer case problems #1 jack up truck place on 4 jack stands. Start and select 4 high position in drive release brake ad watch front driveshaft does it turn "yes" problem is axle actuator on passenger side of differential not engaging axle shaft. "no" apply brakes bring to a stop engage low range does low range work "yes" internal transfer case problems "no" electric transfer case shifting motor failure.

Make sure that the vacuum hose connector is connected AND connected correctly at the transfer case and at the front differential. If that is all right and the front differential still doesn't engage, then you need to test the vacuum actuator at the front differential.

The Selectable Four Wheel Drive (S4WD) Front Axle consist of the following components:
• Differential Carrier Housing
• Differential Case Assembly
• Inner Axle Shaft
• Intermediate Shaft Bearing Assembly (located on the right side of the oil pan)
• Electric Motor Actuator
The front axle on Selectable Four Wheel Drive (S4WD) model vehicles uses a disconnect feature mounted on the right side of the oil pan in order to engage and disengage the front axle. When the driver engages the 4WD system, the Transfer Case Control Module sends a signal to the electric motor actuator to energize and extend the plunger inside. The extended plunger moves the clutch fork and clutch fork sleeve across from the clutch fork outer gear that is splined to the right side wheel drive shaft to the clutch fork inner gear that is splined to the inner axle shaft. The locking of the two gears allows the axle to operate in the same manner as a semi-floating rear axle. A propeller shaft connects the transfer case to the front axle. The differential carrier assembly uses a conventional ring and pinion gear set to transmit the driving force of the engine to the wheels. The open differential allows the wheels to turn at different rates of speed while the axle continues to transmit the driving force. This prevents tire scuffing when going around corners and premature wear on internal axle parts. The ring and pinion set and the differential are contained within the carrier. The axle identification number is located on top of the differential carrier assembly or on a label on the bottom of the right half of differential carrier assembly. The wheel drive shafts are completely flexible assemblies consisting of inner and outer constant velocity CV joints protected by thermoplastic boots and connected by a wheel drive shaft.

How To Install Repair Replace 4x4 Front Axle Actuator Chevy Trailblazer...

There are actually two actuators, one is located in the transfer case and one on the front differential. the one on the transfer case provides power to both front and rear driveshafts, the front actuator must engage so that the front differential locks and provide traction to the front wheels. This means that even if the transfer case is engaged in 4x4 mode the front wheels will not have traction if the front diff actuator is not working.

SOUNDS LIKE A BAD HUB TRY THIS TO DIAGNOSE THE PROBLEM

Put the transmission in park, set the parking brake and raise the chassis so one of the front wheels is off the ground while the other is still on the ground. When the transfer case is in two-wheel drive, the hubs should be released allowing the wheels to turn freely when spun by hand. If the axle shaft turns when you spin the wheel, it means the hub has not disengaged.
To check engagement, rotate the axle shaft backwards. This should lock the hub. Try turning the wheel by hand again. The axle shaft should now turn with the wheel if the hub is locked. If the hub fails to lock, the hub will have to be disassembled and inspected or replaced.
To check release, hold the axle shaft steady and rotate the wheel backwards. You should hear a click as the locking mechanism slides back out and disengages the hub. Rotate the wheel forward again and it should turn freely.
Another way to check the hubs is to raise the vehicle on a frame contact lift so all four wheels are off the ground. Then start the engine and place the transfer case in four-wheel drive and the transmission in drive. If the front wheels don't turn, look at the front axle shafts. If both shafts are turning, but one wheel is not, the problem is a bad hub on the wheel that isn't turning. If the front driveshafts are not turning when the transfer case is in four-wheel drive, the problem is inside the differential (broken side gears) or the transfer case (broken chain, shift linkage, etc.). If the driveshaft between the transfer case and differential is turning, the problem is in the differential. If the driveshaft is not turning, the vehicle is going to need repairs to the transfer case.
Hope this helps.

Is the front driveshaft turning but the wheels are not? or is the noise coming from the transfer case and the front driveshaft is stationary. If the driveshaft is not turning the problem is inside the transfer case. If the driveshaft turns, remove the front differential cover and make sure the gears are not damaged. Before doing that though, If the boots on the axles are torn, chances are that the c/v joints (one or both) have failed. The front diff is an "open type" which means that the wheel with the least amount of traction will receive all the power. If a joint fails there is no "traction": at that wheel so the opposite one will not turn as well. You will see the axle turning but the wheel will remain stationary. If joint has failed, most times it's faster and easier (and not much more $ to buy a complete rebuilt axle). Chilton or haynes manual outlines r&r...not terribly difficult job but if you have any questions about any of it just ask!

The not engaging leads me to believe that the problem is inside the transfer case. To verify that, remove the front driveshaft and engage the unit. if it still stalls the engine that's all you need to know. There should be plenty of used units available in local scrapyards for a reasonable price.

First thing to test is to see if the front driveshaft is getting engaged from the transfer case. With the vehicle in 4x4, and engine shut off, and in park, crawl under and try to turn the front driveshaft by hand. The driveshaft looks like a pipe that runs from the transfer case, located just behind the engine/transmission, to the front differential. If it rotates by hand, there is a problem with the transfer case. Some Jeeps have a vacuum actuator on the front diff that slides a collar inside the axle tube to engage it. I will watch for you findings, and you can leave me another message, and I will be happy to chat back with you on your findings.