I have a 03 blazer LS (non-auto 4wd), just recently my truck will not go into 4 hi, i can stop put it in N and 4 LO works perfectly. If i stop put it in N and push 4hi both lights(4hi,4lo) blink i hear the actuator clicking and then it switchs back to 2hi, never to show 4hi light up by itself. If i am stopped in D or rolling slow 4 hi wont even recognize i am pushing it. Any ideas? I haven't really got into diagnosing it yet but i would like some help as to where to start. Thanks!

 

enocode motor malfunction defaults to 2hi and 4lo(max both ways)..... read the thread.

 

I have the same problem with my 04 or at least that's how it started. One day i was trying get it to shift into 4hi and it shifted into 4lo, and i couldn't get it back into 2hi. I did every troubleshooting thing i could think of. The thing that stuck out to me, if there is a problem it's default is 2hi but it would not shift out of 4lo. I took it a trans shop and they told me that my actuator arm was forzen and from trying to shift it i popped the fuse. They told me that i need to rebuild the transfer case. I had them shift my truck back into 2hi (which was the cheaper route instead of the rebuild that they quoted me at $1200). I don't know if anyone else has had this problem of their actuator arm sticking. If anyone has any idea on what i should do i would love to hear it, winter is coming, and i would like 4x4 to work.

 

I had this happen to my 94 s10 blazer and I was told a bad sensor which I thought it seemed odd sounding... but when I sold it 4hi and 4lo ended up working for some strange reason

 

This is most likely caused by an encoder fault as mentioned above. One thing to check first is that all of the wiring at the switch, the TCCM, and the encoder motor are nice and clean.

 

Alright I will check the encoder motor's cleanliness, if I clean it and still no operation what means of checking the encoder for proper operation do I have?

 

1998 Blazer 4x4 will not shift to 4 high. it shifts to 4 low and back to 2 high. but skips 4H. my mechanic tried to short the pin on the data connector but it kept blowing a fuse on the orange wire. so he had another used tccm he knew was good he let me use and i swapped it. but it still was doing the same thing. i cleaned all the connecter pins, and the connector plug with a small wire rifle bore brush and a tooth pick and blew it out with air. but that didnt help. still same thing. so i swapped back to the original tccm. next, i swapped out the actuator motor on the transfer case. it looked clean in the connector. so i didnt clean it much. pins looked good. after swapping that out i tried it again and same problem. still no 4 high. i jave 4 low still and 2 high. it switches between them and when i hit 4 h it seems to want to go to 4 low instead. all 3 ights work and the buttons seem to work on the dash so i dont think it is the switch. also the 2 high light seems to some times be on and some times off. any ideas ??? im running out of things to swap out !!!

UPDATE !!
I FOUND THE PROBLEM !!
I ran all ofer the country looking for another switch. so not finding one i decided to try another one. well it had different wires after i took mine out. so i took mine apart carefully. just snaps together. I cleaned the contacts on the buttons. snapped it back together, i had the battery ground disconnected so i reconnected. turned the key on and off 5 times. started it and i will be darned .... it is working now.
all that headache and 2 days of work for a 2 minute fix.
well maybe it will help someone else. have a great day and enjoy your blazers !!!

 

pm me your e-mail, I will send you some pdf's

 

noticed today that my truck wont go into 4hi but if i put it in N it will go into 4lo. 4hi button wont even recognize that im pushing it but when i go to shift into 4lo both the 4hi and 4lo lights both blink and then it goes to just the 4lo light. any suggestions???

 

Have you tested the switch or checked the contacts on the TCCM? Testing the switch is easy on the 3-button (NV233) models, but a bit more involved on the 4-button (NV236) models. The tech article section has the necessary info.