Hello
My ride is a 98 Blazer LT 4wd. Anyways when I want to go into 4HI I push the button and nothing happens, no lights, no switch, no nothing. However sometimes when I fiddle with it- like push it many times in a row it finally clicks in, sometimes it wont go in even if i do fiddle with it, other times it goes in on the first try.Does anyone think this is a bad button or are other things getting lazy such as theTCCM (something I dont really want to buy). Ive been reading many post about4WDandconcluded it could be this or theTCCM or possibly a freak thing with the vacume system.The 4Lo optionworks perfectly fine. Thanks for your input!

 

A quick way to find out if it's NOT the SWITCH......disconnect both of your battery cables (negative first) and leave them off for 5 minutes.......then reconnect and see if it will go right into 4HI.

 

Thanks ill try that! That will at leastsave me from buying an unessisary part! I hate throwing money at a problem. (But sometimes buying new things is fun... hehe)Ive been reading more post about diagnosing this somewhat common problem and theres a way to check the codes by grounding pin #13. If disconnecting powerworks andthe problemcrops up again ill checkfor codes. Ive read in one post that if the system faults like 25 or 30 times then it wont allow the truck to go into 4hi, only 4lo. Disconnecting power merly erases these codes and the problem will come up again after so many faults.Correct me if im wrong, but these faults are caused by the encoder motor that sometimes gets "lost" on referencing the shift location in the TC?At least disconnecting power is a good start for process-of-elimination.
Thanks everyone for your support. This site is almost a must for all the do-it-yourselfers who own a blazer, or for people who hate mechanics touching your ride!