I have had this exact same problem on 4 different blazers. The switch goes bad and blows the fuse. if you keep putting fuses in without replacing the switch, it will continue to blow them. I would be willing to put money on the fuse.

 

Brian... The front axle actuator going bad does not cause any problems with the transfer case not engaging 4wd. The actuator controls the locking in of the front axle. If the actuator were to go bad, it could still engage in 4wd at the T-case, but not actually result in power at the front wheels, only to the front axle.

And yeah, if the fuse is good, it could be the encoder motor on the side of the transfer case, or the TCCM (transfer case control module).

 

Hello,

I have the exact same truck 99 zr2 and had the exact same problem so i think this should help.

Does your ZR2 have the Auto 4wd option (the button would be where the 2hi 4hi 4lo buttons are) if it does, (mine did) and I found that my t-case was different that most, most importantly how the vacuum lines are run to lock the front diff.

On my truck, I would push 4hi and it would continually flash and never lock in (the light wouldnt even go back to 2hi) In most blazer Tcases, the actuator for the front diff is fed by a vacuum line from the transfer case, in mine, I found there is an electric switch (valve) located on the firewall under the hood (Right in the middle. It opens vacuum to pull the diaphram and lock the front differential. Check where the vacuum hose from under your battery goes. if goes through a electric valve, I would bet thats where the problem is (thats what my problem was.... the dealership told me it was the buttons inside the cab, which made no difference after they ordered a new one.)

Test the electric valve with a voltmeter. pull the connector off of the electric vacuum valve and push the 4hi button. While the button is flashing put your voltmeter on the 2 wires in the connector. If you are getting 12 volts, the computer and cab buttons are working fine (HURRAY) but the electric valve is not (which is probably a reliefe since its a hell of a lot cheaper to replace than most other components.. probably about $50 and 5 mins to install.)

If this is the case.. the front prop shaft would be turning when you push 4 hi, but the front wheels would not get power because the diff hasn't locked in (but its pretty hard to check that unless you have a lift at your disposal or want to lean out the door and look underneith while driving )


I really hope this helps!!!!

-Bryce

 

You're right. I got confused as I've had two vehicles with 4 wheel drive problems. My Sonoma had a bad actuator under the battery tray. The problem described here where the 4 wheel drive light on the button just blinks and won't engage happened on my 99 Blazer. It was a bad encoder motor. I have no idea what it would cost to fix, cause when it happened on my Blazer it was still under warranty and was free to get repaired. Sorry for the mix up.

 

I don't know if you all know but you guys are awesome. Like I said, I belong to the prerunner forum and issues with my S-10 never got this many well productive answers and replies. You all are coming at me from 20 different directions, but that is awesome!! So now i just have to compile my notes from your replies. The Army doesn't need me this weekend so starting tomorrow, I will hit it head on with definitely what bellert suggested. I am not discounting anyone. I am going to research what you all suggested. Outstanding!! Thank you all so much