2018 GMC Sierra Manual Shift not displayed

[MCastle1]

Hello,

Ive got a 2018 GMC Sierra 1500 4x4. It has the buttons for tow/haul and manual shift selection but it won’t go into tow haul mode, not even an indicator light, and there is not option on the dash for manual selection. Like it doesn’t exist. But Ive only owned it a few weeks and it has 100k on it. It hasn’t been there since Ive owned it. Anybody know anything about this? Thanks

[CamGTP]

For the tow/haul, it could be a bad button. I've seen that happen before, you end up just replacing the shifter assembly with a new button.

 

For manual mode, the shifter should have the +/- buttons on it, pull it down one more past DRIVE and it will go into manual mode.

Edited May 19, 2024 by CamGTP

[MCastle1]

39 minutes ago, CamGTP said:

For the tow/haul, it could be a bad button. I've seen that happen before, you end up just replacing the shifter assembly with a new button.

 

For manual mode, the shifter should have the +/- buttons on it, pull it down one more past DRIVE and it will go into manual mode.

This may be me just not knowing any better, but having driven the heavier dutier versions of gm and fords for work, I thought just by pressing the plus or minus would throw it into manual mode, but not the case here correct? So can it be put into manual mode while driving down the highway or do I need to come to a full stop to shift it down? Thanks for responding. 

[CamGTP]

You can put it into manual mode anytime. If you are cruising at highway speeds in a 6 speed it will auto downshift to like 4th or 5th gear, the 8 speed truck will likely downshift to 6th or 7th and then you can mess with the buttons as you see fit.

[rlcole321]

As for the "Tow" use, since you haven't own it from new, someone could have "Retuned" the ECM/TCM and changed things and now it is disabled. It's very easy to do that with HPTuner.