2022 GMC Siearra Flat Towing Problems

[RVStitchy]

Just got a 2022 Sierra 1500 for flat towing. I am running into a problem and wondered if anyone else has experienced the same.

We just completed a 6 day, 800 mile trip. I connected and disconnected the new truck a half dozen times. I am following the steps in the owners manual to the letter every time.

The first concern (maybe not a problem) is with one of the final steps to go into flat tow mode. After confirming the 4wd transmission is in neutral the manual calls for putting the shift control in Park. When I do this there is a 2 second grinding noise. As if I put it in park while still rolling - have not done that in a couple decades but I remember the noise well. That occurred many times during our trip without any other noticeable problems.

The second issue is far more serious. I was taking the coach back to storage from our house. I hooked up the GMC and drove less than one block. I stopped at a stop sign to turn. When starting the turn I found the right rear tire locked up - 50' of skid before I noticed and stopped. it was not skidding for the first 1/2 block.

I stopped and went through the process of getting out of tow mode and back in per the manual. The truck still had a locked right rear tire. I decided to disconnect the truck and return to the house. The truck drove back without a noticeable problem.

I have an appointment next week with the company that installed the Blue Ox kit. He is extremely knowledgeable and specializes in RV towing. I hope he can find something.

This is the "New Body" 2022 GMC with the shifter in the center console. Not the "Limited" with the shifter on the column.

Any similar experiences?

[Bpeter2]

Originally Posted by RVStitchy

Just got a 2022 Sierra 1500 for flat towing. I am running into a problem and wondered if anyone else has experienced the same.

We just completed a 6 day, 800 mile trip. I connected and disconnected the new truck a half dozen times. I am following the steps in the owners manual to the letter every time.

The first concern (maybe not a problem) is with one of the final steps to go into flat tow mode. After confirming the 4wd transmission is in neutral the manual calls for putting the shift control in Park. When I do this there is a 2 second grinding noise. As if I put it in park while still rolling - have not done that in a couple decades but I remember the noise well. That occurred many times during our trip without any other noticeable problems.

The second issue is far more serious. I was taking the coach back to storage from our house. I hooked up the GMC and drove less than one block. I stopped at a stop sign to turn. When starting the turn I found the right rear tire locked up - 50' of skid before I noticed and stopped. it was not skidding for the first 1/2 block.

I stopped and went through the process of getting out of tow mode and back in per the manual. The truck still had a locked right rear tire. I decided to disconnect the truck and return to the house. The truck drove back without a noticeable problem.

I have an appointment next week with the company that installed the Blue Ox kit. He is extremely knowledgeable and specializes in RV towing. I hope he can find something.

This is the "New Body" 2022 GMC with the shifter in the center console. Not the "Limited" with the shifter on the column.

Any similar experiences?

While I tow a 2020 Denali I have learned from experience in order to stop that GRINDING noise. After you have the transmission in neutral and shift the transfer case into neutral. Before you you shift the transmission back into park and while it is still in neutral. Shut the engine off then shift to Park. This stops that issue.
As far as your brake problem. I can only guess there is something going on with your supplemental (toad) braking system. But only a guess and certainly do not know.

[RVStitchy]

Originally Posted by Bpeter2

While I tow a 2020 Denali I have learned from experience in order to stop that GRINDING noise. After you have the transmission in neutral and shift the transfer case into neutral. Before you you shift the transmission back into park and while it is still in neutral. Shut the engine off then shift to Park. This stops that issue.
As far as your brake problem. I can only guess there is something going on with your supplemental (toad) braking system. But only a guess and certainly do not know.

Thanks. Your suggestion to shut off before shifting to park is exactly what my tow installer said on the phone. Not exactly the order the manual suggests but sounds logical.

Not sure it is the Air Force one system. Only one tire locked based on the skid on the road. I would think both would lock if it was an AF1 problem.

[Bpeter2]

Originally Posted by RVStitchy

Thanks. Your suggestion to shut off before shifting to park is exactly what my tow installer said on the phone. Not exactly the order the manual suggests but sounds logical.

Not sure it is the Air Force one system. Only one tire locked based on the skid on the road. I would think both would lock if it was an AF1 problem.

I like you learned the hard way that the manual wasn't right.
I also have a AF1 in our truck and have not had that problem. However in a previous truck we had. I did have a similar problem with the rear brakes locking up. While it wasn't the brake system itself, it ended up being the cable that hooks up to the brake pedal being out of adjustment causing the issue. But again not sure that would be your issue with only one tire locking up. Could be a number of things. But since it does not happen when you unhook. I would be looking at where on the coach the AF1 air line was tapped into and be sure you don't have a valve bleeding air into the system when it should not be. But again without being there.....just guessing.

[Dutch Star Don]

I don't know if it's still required to disconnect the battery. On my 2012 Silverado, the procedure was to disconnect the battery and then move the shifter from Drive to Park.

TO TOW:

1. Start engine and shift transmission to Neutral “N”
2. Shift transfer case to Neutral “N” (Hold at least 10 seconds)
3. Shift transmission to Drive “D” and insure transfer case is in
“Neutral”, then turn key to “ACCESSORY”.
4. Shift transmission to Park “P” and turn key to “OFF”.
5. Wait 30 seconds and restart.
6. Shift transmission to Drive “D”, turn key to “ACCESSORY”.
7. Disconnect battery.
8. Shift transmission to Park “P” (Leave key in “ACCESSORY”).

[NCC-1701A]

We have a 2016 Silverado and our procedure is same as DS Don's. I put all the steps on a card I keep in the cab as I'd never remember each of the dozen steps in the correct sequence.

One thing my wife and did learn the very first time is to not inadvertantly leave the power windows rolled down while going through the process unless you you want to have to do the "undo" process then the tow process all over again! :-)))

[StaRVGazer]

I had a similar occurance with my brake system. I use the NSA Ready Brake tow bar which uses the cable attached to the brake pedal (no air). Once, when pulling out and getting a few blocks down the road a driver flagged me and told me there was smoke coming from my front wheels. At first I thought I missed a step in the tow set up mode and torched the transmission. Turns out, the swage fitting on the brake cable was hanging up on the hole in the front bumpter where it passes through. So the brakes were being applied even without the tow bar activating the mechanism.

The power brake vacuum booster on cars (as required by DOT) stores enough vacuum to allow power braking one or two strokes after the engine fails or is shut off. The first time the Ready Brake was actuated the cable hung up and there was a enough power assist to keep the brake pedal depressed for a distance. When I freed the cable the brake released. All was fine. In addition to making some changes in the cable entry I now depress the brake a few times to dump the stored vacuum every time I hook up just in case. The Ready Brake, and other devices, has plenty of force to apply braking without the power assist. I suspect that normally it over-brakes the first few stops behind the RV until the residual vacuum is gone.

This may not be your issue but.....another piece of info.

Paul

[Granite17]

I have a 2021 and had the grinding happen once after checking that the truck was out of gear and going to Park.
I now test to make sure it has gone into neutral by placing in drive and revving the engine , same for reverse, brake, then I shift to neutral before shifting to Park. This eliminated the grinding on mine.

[Suburbazine]

You probably want to install a battery disconnect on the 2022. The newer trucks (I think 2018 onwards?) have a "feature" where they lock the brakes while the truck is in park if they sense the key nearby. Supposed to keep the truck from rocking while loading passengers and equipment.



As for the grinding which many have correctly addressed already- the hydraulics in the transmission will allow it to freewheel when there is no load on the output shaft and the torque converter is spinning. You're not really dropping the parking pawl on a moving vehicle, but the speeds of the transmission rotation are going to be very high. I forget what the calculated internal rotation looks like in neutral (it may not be even close with an 8/10/whatever speed) but for a 4 speed I think it would freewheel up to the equivalent speed of coasting in 2nd gear at idle.

[RVStitchy]

Originally Posted by Suburbazine

You probably want to install a battery disconnect on the 2022. The newer trucks (I think 2018 onwards?) have a "feature" where they lock the brakes while the truck is in park if they sense the key nearby. Supposed to keep the truck from rocking while loading passengers and equipment.



As for the grinding which many have correctly addressed already- the hydraulics in the transmission will allow it to freewheel when there is no load on the output shaft and the torque converter is spinning. You're not really dropping the parking pawl on a moving vehicle, but the speeds of the transmission rotation are going to be very high. I forget what the calculated internal rotation looks like in neutral (it may not be even close with an 8/10/whatever speed) but for a 4 speed I think it would freewheel up to the equivalent speed of coasting in 2nd gear at idle.

Thanks for all the good feedback.

Got the battery disconnect under the hood. Big marine type switch. \

I have an appointment this week with the Blue Ox installer the run through the set-up and see if we can replicate the problem. Will post if we figure anything out.

[Bpeter2]

Originally Posted by RVStitchy

Thanks for all the good feedback.

Got the battery disconnect under the hood. Big marine type switch. \

I have an appointment this week with the Blue Ox installer the run through the set-up and see if we can replicate the problem. Will post if we figure anything out.

I am not sure about the Sierra, but my (Sierra) Denali has the push button start. Along with having electric power steering, it also has an electric steering wheel lock. That steering wheel lock activates when you open the drivers door. That requires me to have the battery disconnect inside the cab so it can be disconnected before the door is opened. So I used the Roadmaster electric disconnect to solve that issue.

[FSU Camper]

I have a 2020 Silverado and found I must follow this particular order to keep the parking break from automatically engaging.
1. Engine on, shift to neutral
2. Press 2H five times quickly - verify transfer case is in neutral
3. Shut engine off
4. Disconnect Battery (I too have a remote disconnect) - make sure door is unlocked
5. Shift to park.
6. Roll truck back to lock tow bar

Not sure how much bus changed on the 22 but beware of the electronic parking break.
Good luck, sounds like a very nice tow setup.

[RVStitchy]

Update from the OP:

Finally had time to go back to the original Blue Ox installer. This guy really knows his stuff. I would highly recommend him if you are in South Florida looking for help with flat towing.

We went through the manual step by step. Since this is a "new body" 2022 they have only been out a few months so he has not seen many of these. The grinding that I described when taking the final step going into Park is still there. He recommends NOT changing the procedure in the manual and living with it. He would not deviate from the steps in the manual. He is concerned that there are reasons for the steps that we can't see such as electronics or sensor activation/deactivation.

We went in and out of tow mode and had successful trips around the block without an issue (other than the grinding noise). He noticed scoring on my rear brake discs on both sides. Remember my main concern was a left rear lock up at low speed only a tenth of a mile from my house. He speculates that I might have forgotten to release the electronic parking brake. It might have been engage and allowed some wheel turn for 100 yards before heating up and locking the tire. The scoring on both rear rotors is obvious. Front rotors are perfect. I should mention here that I have less than 400 miles on the truck.

I accept that as a possibility and the only logical explanation. I created a cheat sheet on the steps in the manual that is easier to access than thumbing through pages. I have added a final step in my cheat sheet: CONFIRM: Trans in Park, Transfer Case in Neutral, Parking Brake Off!

I am going to talk to the GMC dealer about the grinding in park and see if they can come up with an explanation.

[sramer]

I am going to talk to the GMC dealer about the grinding in park and see if they can come up with an explanation.[/QUOTE]


As far as this issue grinding issue. I have a 2022 Escalade which is the same procedure.

When you put the Trans in gear after the transfer case is in neutral it spools the panetary gears in the transmission which are connected to the output shaft. Now that the output shaft is disconnected from the transfer case it's spinning freely because you have put it in drive and reverse to check for no movement.

When you put it in park right away you have essentially done same thing as putting the truck in park when rolling and you get that grinding sound because you engage the parking pawl.

The key to avoiding this is to put the truck in natural, wait about 10 seconds then put it in park. You will be good to go with no more grinding.