Today as i was putting the truck in reverse i accidently hit the 4hi switch and a clanking noise started i put it back to park and turned off the truck and started it back up and now as i drive at about 20mph or so ill get a clanking noise i looked under and everthing looks normal. What could it be for one and how do i know for shure that its back in 2wd since the leds work when they want on the swicthes i hit the dash and they we turn on.


Thanks

 

I realize this is a very late reply, but in case anyone searches for this problem later...

I inherited a 2003 Blazer and just before heading up a steep hill, decided to try the 4Hi for the first time. Heard something between a click and clank that seemed to keep pace with the wheel speed. Sounded like it was coming from the front left.

Tried 4Hi again a few days later on a flat surface and the click had definitely become a clank -- sounded like something was about to fall off. Noise disappeared when I went back to 2Hi.

Took it to my fav mechanic and it turned out to be the front left axle. Joint was worn and loose but was only affected when it was under tension, ie, 4-wheel-drive.

The part was about $1000 retail, but I went with a $747 re-manufactured. Needed 0.6 hours labor.

Problem seems to be solved.

 

$747 ? What exactly was replaced?

 

4wd Front Axle Clicking When in 2HI - Goes Away when in 4HI/4LO

Found along with a few other useful 4wd threads and with many other threads on common issues in these trucks in the Tech Article (DIY) section!

 

Mine was just the opposite. Quiet in 2Hi, click/clank in 4Hi.

Part replaced was the left front axle.