Good day all, been reading this forum for a while so decided to join since I didn't see my specific problem in the search.
So my daughter bought a 2001 Blazer about 2 years ago with 175,000 miles and it has run great. Almost, that's another Thread!
So I just happen to come across one from an older gentleman and I now own one as well, it's a 1995 with only 110,000 miles, mans been sick and it was sitting for a year and not run for 6 months. Garage kept no dings scrapes or dents had to jump start it and started right up and other then the first 15 seconds runs smooth.
Problem. It switches from 2HI to 4HI no problem, switching to 4LO takes a while. You have to hit the button several times or hold it and it will go into 4LO one out of every 10 times or so. No blinking just right into LO or nothing.
Would a vacuum leak cause LO not to work and HI to work perfectly?

 

no - try checking the plugin at the switch and at the tccm both plugs are well known for corrosion

 

Since I'm pretty handy with a meter and electronics do you know what the wiring schematic for the switch is so I could check it out if I'm removing the plug?
Thank you.

 

Since it was an easy remove I did and tried cleaning the terminals with a small knife and even tried to remove the cover off the back of the switch but thought better. Anyway it seems to be working better, it will go into 4 low about 8 of ten times now with the other times the 4 low light comes on and the 4 high blinks until I hit the low button again, then it goes into low. I am assuming the switch has issues??????
Thank you.