4x4 high but low doesn't work

[War shaman]

Ok I have a 2001 silverado LS that when I push the 4 wheel high button you can hear the actuator lock in and the button indicates that it is locked in. But it will not do anything but flash when I put it in to 4wheel low. It flashes then goes back to 2wd. With no actuator noise or anything. So question is do I need an actuator or is something else wrong? I have replaced the button because I had a new. I don't understand if it works for 4high then why not 4low ? So this is why I asked

 

[B-train]

Not to question your intellect, but are you shifting into neutral before shifting to 4 low? I had the same truck years back and always went from 4 hi to 4 lo in neutral

If that doesn't help, then a scanner is needed. Probable culprit could be the shifting actuator

 

[Sam Harris]

I’d get a Tech 2 on it, to determine any codes, and it should also be able to communicate with the t-case. Mine had acted funny since I bought it in 2018, randomly showing in neutral, 4-hi, and eventually 4-lo when starting up, which finally caused me to fix it. (Also randomly showed “Service 4WD” on the DIC, but I don’t believe you have that in your ‘01) My fix was very easy and cheap, a new encoder ring for the transfer case shifter motor.
Note: for the most part, my display / buttons were incorrectly reporting the t-case position.. I was not actually in 4-lo, when it showed 4-lo, but at the time, living in Colorado, and wanting to use the 4-hi if needed, it was not reliably available when trying to shift to other modes.

 

[Sam Harris]

Not to question your intellect, but are you shifting into neutral before shifting to 4 low? I had the same truck years back and always went from 4 hi to 4 lo in neutral

If that doesn't help, then a scanner is needed. Probable culprit could be the shifting actuator

I read the post, and didn’t even think of this! Definitely needs to be in N (Or possibly P..?), to shift into 4-lo..!

 

[B-train]

Yes, shifting in a gear loads up the driveline from what I remember

 

[mb1500]

Best practice is to be in Neutral while slowly rolling forward only a few mph when engaging 4LO.

 

[War shaman]

Not to question your intellect, but are you shifting into neutral before shifting to 4 low? I had the same truck years back and always went from 4 hi to 4 lo in neutral

If that doesn't help, then a scanner is needed. Probable culprit could be the shifting actuat

Lol questioning my intellect now I hadn't thought to put it in neutral. I always put it in park but yes now I have tried it in neutral and same result

 

[B-train]

10-4. Probably going to need a scanner to check commands, etc.

 

[Fless]

As stated, there's a specific procedure to safely enter 4-Low mode: