1999 Blazer 4x4 HI no longer works
 

First off hello... I am new to the forum, I searched for a category to introduce myself so my first post was not a question but I did not find one.

Having said that, my 4 wheel HI stopped working yesterday. There has been a clicking sound (similar to a relay) under the passenger side dash for approximately 3 years. The clicking sound was constant, it would usually speed up when I hit the brake or blinker. My friend who is a "mechanic" told me it had to do with the ignition and not to worry about it. When my 4 wheel HI stopped working the clicking stopped. No more clicking, no more 4x4 HI... Here is the kicker, my 4 wheel LO works but only if I have it in Neutral (not sure if it is supposed to be like that). After clicking 4LO (only while in neutral) 4HI and 4LO click a couple times then it engages. There has also been a couple times that I have engaged 4LO then clicked 4HI and the button lights up but when I drive it goes to 2 wheel drive. Any advice would be greatly appreciated... Thank you

Sounds like you may have an encoder fault, but there are other things to check first. Start by removing the TCCM and inspecting the electrical connections. It is located behind the passenger side kick panel. After that, have a look at the OBDII non-automatic transfer case diagnosis in the Tech Article (DIY) section.

Thank you sir... I will get on that when I get a chance. I appreciate your help and I will keep you updated. Thank you!