just bought a 99' blazer yesterday and was driving to work today and noticed the the 2wd indicator light was'nt on. I tried to shift it into 4wd at a stoplight and nothing happened. the truck drives great but has a one good tire and 3 with like 4-5/32nds, would this mess with the wheels speed sensors and not let it shift or is something else going on? also has a ses light on that I'll checkout after work. any help would be appreciated.

 

There needs to be a pretty significant difference in tire diameter to affect the 4wd. You should try shifting from 2HI to 4HI while you are moving slightly to see if it helps.

What transfer case do you have (3-button dash switch == NV233, 4-button dash switch == NV236)?

 

4x4 auto, 2w high, 4w high,4w low. so that would be the nv236.

 

The bad part about that (NV236) is that you need a full feature scan tool (Tech2 or equivalent) to be able to access the TCCM to read codes stored. The "service 4wd" light would be lit if you had codes stored in your TCCM.

Have you tried to engage 4HI while rolling? If not, try that.

Also, are there any lights lit on the dash switch? Do they just blink and return to 2HI?

 

ok. heres what happened on the way home. it seems like all the indicator lights for 4x4 turn off when driving over 25-35 mph, but under that it works fine. so, i dont know whats going on over 35 but it definetly works when going slower. 4w low i'm not sure about yet. also the battery is junk (113cca) and all the lights dim when shifting the t-case, will fix that asap. no noticible issues when i had it in my shop today,but i only have a generic scan tool. my buddy has a genisys that updated to 06' think that might help? also, the abs light is like half lit (dim) it may be a glitch but i'll scan it with the genisys and find out.

 

If the engine is running, the lights should not dim when you try shifting the transfer case. It sounds like you might have a problem with your charging system...

 

charging system is fine (14.4v) battery is junk, got a new one to put in today. the lights dont blink and return to 2high, they just randomly all shut off and then randomly come back on.

 

I would pop out the switch and check the wiring connection at the back. Also remove the passenger side kick panel and inspect the wiring connections at the TCC. Sounds like a connection issue.

 

I'm starting to think its just the switch to. NAPA sells the switches for about $20.