1990 CHEVY 1500 4X4 DOESNT ENGAGE PLEASE HELP

nothing happens. The transfercase seems fine, it goes into each gear fairly easily sometimes a mild grind? but you can feel it engage into gear. the 4x4 light on the SHIFTER doesnt go on. 2wd light works fine. I checked fuses, and damaged wire. Driveshafts lock and turns when in drive, but front wheels dont lock. I replaced what I was told was a bad acctuator, and nothing. there are no vaccum lines anywhere on transfer case, or front diff. just breathing hoses, otherwise it's all electrical. Can I convert to manual locking hub. There is no switch to engage 4x4 just shifter. IM LOST

put the truck up on stands, turn the ignition on, shift it into 4wd, unplug the actuator and look for 12V.

if you have 12V:

pull the actuator, plug it into the harness and see if it pushes it's plunger out.... if no, actuator is bad; if yes take a 1 ft long wooden dowel and push the plunger inside the diff in, if it engages smoothly or requires a slight rotation of the tires to engage your axle is ok, if it won't engage, or the plunger is stuck in, you're bound for some expensive repairs to the front axle..(I've been told the word nightmare comes to mind).

if you didn't get 12V:

double check the key is on, reach up on top of the xfer case and unplug the connector, probe the brown wire (should be the center one). if you have 12v, replace the switch on the xfer case, if no 12V keep looking up the line.

HTH, Bret

nothing happens. The transfercase seems fine, it goes into each gear fairly easily sometimes a mild grind? but you can feel it engage into gear. the 4x4 light on the SHIFTER doesnt go on. 2wd light works fine. I checked fuses, and damaged wire. Driveshafts lock and turns when in drive, but front wheels dont lock. I replaced what I was told was a bad acctuator, and nothing. there are no vaccum lines anywhere on transfer case, or front diff. just breathing hoses, otherwise it's all electrical. Can I convert to manual locking hub. There is no switch to engage 4x4 just shifter. IM LOST

I don't know if its the same problem, but a similar thing happened to me on a 92 siverado 4x4. I had to have the 4x yoke changed out to a different replacement part as the original part was known defective. Of course Chevy didn't pick up any of the cost, even though they sold a defective product. In their defense, it did last 7 years before it failed. I don't remember what it cost, but it wasn't cheap. Over $400.

Using a doll rod doesnt seem to logical if the actuator works does it?