When I switch from 2h to 4hi the switch does not flash

When you push the 4-Hi button, it shouldn't always flash. Usually, it will just switch right over in a second or two. If you do it with the key on, engine off, you should hear the transfer case actuator move under the truck. This usually isn't a problem. If you don't hear that though, you likely need a Transfer Case Control Module ($50.00 at the local junk yard). The TCCM is a fairly common problem, but not as common as the front axle actuator. The best test that I know of is to have someone engage the 4x4 while you look for voltage with a multi-meter or voltmeter. If there's no voltage there, then the TCCM is the likely culprit.

The vacuum controlled front axle actuator is what locks the front axle and engages the wheels. Since it uses a vacuum bladder, it dries out over time and starts leaking, which keeps the front from engaging. This actuator is under the battery tray. When it fails, the light will come on when you switch to any 4x4 mode and stay solid. You will hear the transfer case actuator engage too. Essentially, the truck thinks that it's in 4x4, but it's not there. When mine broke, I simply removed the actuator and started using a pair of pliers to pull the cable into 4x4 mode and then I put a pair of vice grips on it to lock it in. Works like a charm, and since I only use it once or twice a year, it doesn't really bother me to do that since I'm saving about $100.00 in parts.

I'll get back on later with more specifics and images and such. For now, the wife is talking at me ;)

Glad to be of assistance! That cable only comes out maybe half of an inch, so don't expect it to move much. You should feel a click when it's in the right position though. If it won't click into position, put some wheel chocks in front of and behind one of the wheels, put it in neutral, and try it again. I've been using Blazers on rural mail routes for four years now and I am more than a little familiar with their quirks. By far, they are the toughest light duty trucks that I've seen, and I've been in and around the car business since before I could walk. They have cosmetic type issues, and go through some fuel pumps and front axle actuators, but mechanically they are about as solid as can be. Anyways, feel free to come back anytime and send your friends too! Good luck.

Harry.

Personally I would wait for the front actuator to be installed and see how everything goes. Replace the next thing that holds it up. You might go ahead and get all of the parts together and return whatever you don't actually need. I don't often replace things that don't absolutely need replacing, but then again mine is a mail route vehicle, more a daily driver, and I beat the snot our if it every day. Just my $.02.