Another 4wd problem

[blakeorr]

I have a 98 blazer 4.3 vortec 4x4. Recently I can not get it to go into 4wd. I have read many posts with people having similar problems but can not pinpoint what my problem is. I was out ice fishing and while driving off the ice in 4wd I hit a large bump as I came to shore and it kicked into 2wd and will not go into 4wd any longer. When I push the 4wd button the TCCM will click and the 4wd light will flash 3 or 4 times and then go back to 2wd. If I repeat this (keep pushing 4wd High) the 4wd button stops blinking and I only get one click from the TCCM and nothing else. I have replaced the TCCM but that has not made a difference. Any advice as to what the problem could be? Any help as to where the 4wd drive components are located and what things should look like? I just dont want to take it in not having any idea and spend or fortune while a mechanic wings it on my wallet.

thanks,
Blake

[old_master]

Can you hear the encoder motor trying to shift the gears in the transfer case when you select 4WD? If not, check the fuses and the connectors to the encoder motor, (located on the transfer case). It may even be a faulty encoder motor. Sometimes you can remove it, clean and lubricate it, and it works fine. If not, it might be time for a new one. Worth a try though, as the encoder is not cheap.

[mgty3whlr]

also check the actuator at the front axle.

[2percent]

Im not sure if 98 is but my 95 is vacuum controlled I lost 4wd becasue a line came off

[Persistent One]

i had the same problem with my 85, a vacuum line came loose off the 4x4 module