89 Sierra 4x4 inoperable

the lights in console fail to light up when i put 89 2500 in 4H or 4L. I checked fuse it appeared good but I replaced the 25 amp fuse anyhow. Is there another fuse or something that controls the 4 wheel drive.

Is it just that the lights wont light or is this not going into 4wheel drive?

The front axle actuator is known to be a problem in these models. Have you noticed a long delay in engagement before this?

There is a new part to solve this problem, check with a GM dealer. It requires a new wire harness also. The original actuator needs to heat up a gas to make the plunger move to engage the front axle. Over time its just get weak and can not longer move it. The new one is electical and is instantaneous.

Check into that, its a well known problem from 88 to circa 1996.

The 4 wheel drive does not work, last year got a new transmission and had one of front axles replaced so I would think mechanically it is good. I do not use the 4 wheel often so do not know how long it not functioned.