2020 GMC Sierra 1500 4WD 6.2L Settings for "Pull Through" Carwash

MrGadget · August 21, 2020

I purchased my first 4WD truck in February (2020 GMC Sierra 1500 4WD 6.2L 2 speed Transfer Case). I wasn't really in the market for a 4WD model, but had to choose one to get the options I did want. So I am unfamiliar with the proper use of 4WD. Specifically:

1) When just driving around town and not towing anything, should I leave the transfer case setting set to 2WD or 'Auto?'

2) The manual recommends not using a automatic carwash without giving a reason. Is there a real 'danger' in using one leaving aside the need to choose one that can handle the size of the truck (I've read the posts about leaks, but that is a different issue for me)?

3) My research suggests that if I were to have the truck towed or pulled through a carwash by rollers behind the front wheels that I should put both the transmission and transfer case in neutral. Is that correct? Anything else I should do (besides turn off the auto windshield wipers setting and keep my foot off the brake)?

I did search this forum (and the Internet) trying to find the the answers to these questions, so if I missed something, please forward a link.

TIA

davester · August 21, 2020

The owners manual will have info on when to use 4wd. Just driving around in good conditions, you want to use 2wd.

If you have an antennae, that can be damaged, same for mirrors, depending on which ones you have (tow mirrors are probably more easily damaged as they stick out further).

Z45 · August 21, 2020

2-speed Autotrac Transfer Case

2WD HI mode
- Vehicle operates in 2-wheel drive
- In this mode the transfer case & front driveline hardware are disengaged to improve fuel economy
- Suitable for routine driving on all road surfaces
4WD Auto mode
- 4WD Auto enables the transfer-case to provide the performance benefits of a full time active AWD system
- The 4WD Auto controls automatically adjust torque in response to parameters such as driver inputs, wheel slip control, vehicle dynamic state (understeer/oversteer)
- Ideal for wet or wintry conditions, but can be used on any road surface. Suitable for light off road usage
4WD HI mode
- Transfer case engages front driveline and power is transferred to both the front & rear axles
- In 4WD HI the transfer case clutch maintains higher preemptive torque levels for increased traction vs 4WD Auto
- Suitable for use on slippery road surfaces or off-road conditions such as deep sand, snow or rough terrain
4WD LO mode
- In 4WD Low the transfer case clutch maintains a high preemptive coupling torque to maximize traction and improve wheel control when climbing or descending steep grades or obstacles
- Suitable for off road usage, steep terrain, deep snow or sand
- Ideal for off road driving to maximize low speed traction and increase control on steep grades
Neutral
- ONLY used for towing vehicle (Dinghy tow & Dolly tow capability)- allows vehicle to roll freely
May require additional optional equipment

Z45 · August 21, 2020

Quote

My research suggests that if I were to have the truck towed or pulled through a carwash by rollers behind the front wheels that I should put both the transmission and transfer case in neutral. Is that correct?

NO, just put it in neutral for car wash.

Duramax3oh · August 21, 2020

Agreed to above:

1) Keep it in 2WD for normal day to day driving

2) Drive thru car washes not really a problem, size permitting. Watch antennae and mirrors (I have regular mirrors and oem antennae and don't do anything to them). The brushes can leave scratches on your truck, any truck, any vehicle for that matter.

3) Once on the drive thru track put it in N-neutral. There are usually signs and/or a person reminding you.

MrGadget · August 21, 2020

1 hour ago, Duramax3oh said:

Agreed to above:

1) Keep it in 2WD for normal day to day driving

2) Drive thru car washes not really a problem, size permitting. Watch antennae and mirrors (I have regular mirrors and oem antennae and don't do anything to them). The brushes can leave scratches on your truck, any truck, any vehicle for that matter.

3) Once on the drive thru track put it in N-neutral. There are usually signs and/or a person reminding you.

Thanks for the response. So I'm taking "N-neutral' to be the transmission. What should the transfer case be set to? I plan to only use brush-less carwashes (felt strips). Again, thanks for answering.

0

Z45 · August 22, 2020

Leave the transfer case alone, put the transmission in neutral. DO NOT place the transfer in neutral. My advice, never put the transfer into neutral. No need for that unless vehicle is being towed UNOCCUPIED as described below.

Neutral

ONLY used for towing vehicle (Dinghy tow & Dolly tow capability)- allows vehicle to roll freely

Vehicle being dingy towed

Dolly towing

Edited August 22, 2020 by elcamino

cltsig · August 22, 2020

How do you put the transfer case in neutral?

davester · August 22, 2020

Your owners manual will have easy to follow instructions on how to shift the TC into neutral if it can do that.

Z45 · August 22, 2020

From Owners manual

WARNING

Shifting the transfer case to N (Neutral) can cause the vehicle to roll even if the transmission is in P (Park). You or someone else could be seriously injured. Be sure to set the parking brake before placing the transfer case in N (Neutral).

N (Neutral) : Use only when the vehicle needs to be towed.

Edited August 22, 2020 by elcamino

Duramax3oh · August 22, 2020

Sorry for any confusion... LOL yes change the transmission from Drive to Neutral and let the automated track pull the car through.

redwngr · August 22, 2020

16 hours ago, MrGadget said:

Thanks for the response. So I'm taking "N-neutral' to be the transmission. What should the transfer case be set to? I plan to only use brush-less carwashes (felt strips). Again, thanks for answering.

Transfer case in 2wd.

Transmission in N.