2020 Sierra 3500 srw. Won't go into 4l

Bobnlee1 · January 17

My 2020 Sierra 3500 won't shift into 4wd low. Stopped in neutral still no go. Shifts into 4wd high and back to 2wd. Any info would be greatly appreciated

newdude · January 17

11 minutes ago, Bobnlee1 said:

My 2020 Sierra 3500 won't shift into 4wd low. Stopped in neutral still no go. Shifts into 4wd high and back to 2wd. Any info would be greatly appreciated

Are you getting any messages on the dash when you try to do it? Like "service 4wd" or anything?

So engine on (or just ignition on), vehicle not moving or going no faster than 2mph. Shift the transmission into neutral, then press the 4LO button and wait for the message that the shift was made. You should also see the traction control and stabilitrak lights come on showing they are disabled.

Edited January 17 by newdude

Bobnlee1 · January 17

Nope nothing. Truck running in neutral and push 4low nothing happens no messages. Goes to 4 h and 2wd but no go for 4l..had to change out the battery last month and after I did got a message to service parking brake and now this

newdude · January 17

19 minutes ago, Bobnlee1 said:

Nope nothing. Truck running in neutral and push 4low nothing happens no messages. Goes to 4 h and 2wd but no go for 4l..had to change out the battery last month and after I did got a message to service parking brake and now this

Check engine light on? Parking brake warning? I'm wondering if there's a code or codes in a module that are preventing this.

Bobnlee1 · January 20

Code saying control module. My buddy who is a mechanic believes it's because of battery being switched out. Older vehicles you can switch out quickly new ones he says to unhook battery for a few hours and let everything reset. I will give it a go