when ign.on,or running at dead stop,
my truck is in 2wd by default,when i
push the button for 4wd high i can here it
engage and the light comes on as it should,
but when i push the 4 wd low button
i can not here anything, and the light flash's
for about 30 sec.and then goes to 4wd high,
no codes on scan,

03 sierra, ext.cab 5.3
thanks for any help

 

Do you have the transmission in neutral when attempting to engage 4 low? 4 high can be done on the fly, but you likely have to stopped in neutral to go 4 low. Did it work previously?

 

dead stop in park,i don't knowif it worked when i bought
it a couple of weeks ago, i know i tested auto 4w,
2whigh,and 4 high, i might have missed pushing the 4 low,
talking to the salesman.i bought a lifetime drivetrain
warrenty, but it take's 4 mo's or 4000,miles before it will
take effect,if not using it will not hurt the truck,
then i will take it in afyer the warrenty kicks in.
i was just currious as to why i don't here anything
when i push the 4lo button

 

i have an 01 sierra z71. its been a while but i am pretty sure the truck needs to be in neutral and rolling slowly and then punch four low to get it in that gear.

hope this helps.

 

yelp that worked