Hey guys,
I got my blazer back from the transmission shop after having the revised TCC regulator & isolator valve replaced. It seems to be doing the job but after they were finished they took it out for a test drive and they put it into 4wd for some reason. Of course it got stuck in 4hi and will not return to 2hi. The owner of the shop said that it is still in 2hi even though it says 4hi on the push button.

I can tell it is in 4wd because it is driving differently and it starts shaking when making sharp turns etc. and most the time if the display says it’s in 4wd then it is, oh and the front drive shaft isn’t turning…

I’ve been trying to put it back into 2hi but when I push the button it start clicking for about 5 sec. then returns to 4hi. I checked all the fuses (in the cab & under hood) and they all seem fine.

I took out the ATC fuse and the CTSY LP fuse, waited about 30min, put them back in, shifted the ignition on-to-off 5 times, and nothing changed.

Does anyone know what the fuses AMPF (25A) and HVAC (20A) are for because their missing. I have a fuse for HVAC1 so I’m not sure what HVAC is for… I know what HVAC stands for and what it is just not the second missing fuse.

Do my problems sound like an encoder motor or a TCCM. I’m going to be checking my TCCM because maybe something happened to it while the dash was off when I was changing the heater core.

I could not find the vacuum hoses by the distributor cap but I’m going to be checking the vacuum actuator later since I don’t have the right tools up here to remove the battery tray.

I need some advice on this… I’ve searched and read many posts but none with the final solutions. I’m always great full. Thanks

 

Check your vac lines.

 

no one???
check fuses like stated. check vacuum actuator and it looks good. I need to get it out of 4hi and I read on a post that I can remove the 4wd fuse and it will go back to 2hi. Is that true. Yes/No thanks

 

check all the vacuum hoses little cracks or broken ones will cause insufficient vacuum not allowing shift ability back to 2hi..if all checks out then you are probaly looking at a encoder motor which does the shifting for us instead of the ol fashion lever..listen for transfer case noise..and also the click from the tccm you need to hear both and should hear both when you click the button..try not to drive the truck to much with it stuck in 4hi on dry pavement you'll end up with to much drive shaft wind up which is no good for the gears in the front axle

 

Bet you missed the fact that this is a two year old thread.