4 wheel drive wont engage 93 k-1500

[430Ksierra]

I've been blessed with a 93 sierra that has now turned over 431K and is still going strong. Today I went to the beach, 4 wheel drive engaged immediately (there have been times that I have had to cycle between drive and reverse a couple of times to get the front diff to engage). When I went to leave, the light was on, went off as soon as I put it in gear, and never engaged again. Doesn't even sound like it is trying. When shoud I begin?

 

[Z15]

There is an actuator on the front axle that has been a problem with 90's model trucks. 90% of the trucks had problems with the early style actuators prior to 1997ish model year.

The reason it can take time to engage is because of the actuator design. When you shift into 4x4 electrical current heats a small gas cylinder which in turn pushes a plunger to engage the front axle. Over time these become weak and or fail and the actuator no longer works. The newer models eliminated the gas cylinder but also require a new wire harness and some minor modification to install. Use to cost upwards of $200+ for the GM dealer to retrofit a new actuator (mainly due wire harness and actuator parts costs) but I have no idea what it cost today. Some parts stores sells replacements that are cheaper but better???