1988 chevy 4x4 actuator

The actuator has a spring that is known to break easily in mid-late 90's chevy's.

Ok I know this question is old but for any one else who has this problem, I want to clear some info up. GM did not use vacuum on the 4x4 systems on the full size series. Only used on the S series (S10, S Blazers). Here is how to accurately trouble shoot these problems with the full size 4x4. Remove the front actuator from the front axle ( keep it plugged up and let it hang). Put the T-Case in 4x4 Hi or Lo doesn't matter. Turn key on (don't start the engine) . Now check the actuator to see if it has extended. If (no) now check the plug to see if you have current . If you have current to the plug, change the actuator. Problem solved. If no current to the plug. Check for broken wires ( fix if any) If no broken wires. There is another switch on the T-Case that sends power to the actuator Replace it.. Back to the actuator.... If everything checked out and actuator works. With the T-Case locked in 4x4, try to turn the front drive shaft by hand. With the T-Case locked in 4x4 you shouldn't be able to turn the drive shaft. If drive shaft doesnt turn the T-Case is in good shape and the problem will be in the front differential. In these cases the most common problem is an exploded thrust washer. At this point the front differential needs to be rebuilt. Back to the T-Case..... With the T-Case locked in 4x4, if the drive shaft spins, the problem will be in the T-Case and at this point the T-Case will need rebuilt......... I hope you get the information you need to troubleshoot the GM 4x4 issues.

unplug thae actuator,unscrew it from the axle,plug it back in and engage the 4x4 ,plunger should extend,if it does the trouble is in the housing(washer out of place)

on that truck your fuse for the instrument panel is the same for that actuator.

Have you checked the vacuum actuator under the battery? Battery acid will leak down and cause all kinds of issues with them.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

no it does not

control module behind the passenger side kick panel

Replace the control switch.

thats common in old trucks, if its not the builb its the actuator

Replace the selector switch assembly. Common failures.