How do I test the actuary switch used to engage the front axle for a 1996 GMC pickup with 4 wheel drive

• Shifting from 2HI to 4HI Press and release the 4HI button. This can be done at any speed, and the front axle will lock automatically.

• Shifting from 4HI to 2HI Press and release the 2HI button. This can be done at any speed, and the front axle will unlock automatically.

• To shift from 2HI or 4HI to 4LO, the vehicle must be stopped or moving less than 3 mph with the transmission in NEUTRAL

• Hope this helps.

2002 chevy s10 4 door 4x4 4 wheel drive wont engage

have a 95 k3500 4x4,when i shifted to 4 hi,would not engage.never once heard any type of noise in the front end.replaced both actuators,fuse is,front will not engage.please advise.ken at 989-560-1906.or [email protected] thanks

Sounds like your front axle is trying to engage but does not engage fully.check your vacuum going to the t-case switch and then if that is ok check your vacuum at the front axle actuator.It is located under the battery tray.

actually that first soultion is wrong it is correct on smaller pickups but on the full size pick ups they use a differnet sytem
there a electric actuator on front axle
there be two elctrical plugs on front axle u want the bigger of the two other one is just to turn the 4 wheel drive light on
un plug actuator then remove actuator after it removed plug it back in but leave it out of axle turn key on and shift down to 4 wheel drive the actuator should move out if it dont that your problem if i does move this isnt your problem it either the tranfer case or in front axle

You probably have blown drive hubs. Do you have to engage the hubs at the wheels? If not and they are automatic locking and they are probably blown or seized into the unlock position. They are not too expensive to replace with manual locking hubs (My Suggestion) but the autolocking hubs are expensive. When you take the caps off the front drive spindles and try running it again you may see the axle turning inside but not the wheel. That is the best test. Wish you luck!!

check the hoses on the front axle they are what really engage the 4 wheel to the front axle check for cracks or replace entire line i had that problem before sometimes not enough vaccum pressure

Test it by setting the rear end up just barely off the ground with some jack stands and setting the hubs to lock (if they are manual). Put it in 4 wheel and try to drive away. If the vehicle does not move then very carefully have a helper check and see if the front drive axles are spinning while it is in 4 wheel and in gear while running.
Spinning axles... hubs are at issue
No spinning axles... Transfer case issue.

Theres a vacume dash pot under the battery box. It pulls a cable that engages the front diff. Put the vacume line and you'll have lights and four wheel drive. (it happened to my blazzer)

The vacuum actuator under the batteru could be bad