Battery disconnect switch on 3.0 diesel 2021 GMC serria so it can be towed

[Tim McGraw]

Has anybody installed a battery disconnect switch on a 2021 GMC 1500 Serria diesel to flat tow?

 

[seamus2154]

I dont know what you mean to flat tow? But I have added a battery lead to the rear for a winch hook up on my trailer. 

[2016 Sierra Owner]

2 hours ago, seamus2154 said:

I dont know what you mean to flat tow? But I have added a battery lead to the rear for a winch hook up on my trailer. 

Flat towing is pulling a vehicle on all 4 tires like behind an RV.

 

[TxTruckMan]

Why would you want to disconnect the battery?  I've never heard of that.

[redwngr]

1 hour ago, TxTruckMan said:

Why would you want to disconnect the battery?  I've never heard of that.

 

The need to disconnect comes with the change to electric parking brake.

 

 

To dinghy tow:

 

1. Position the vehicle being towed behind the tow vehicle, facing forward and on a level surface.

 

2. Securely attach the vehicle being towed to the tow vehicle.

 

3. Apply the parking brake and start the engine.

 

4. Shift the transfer case to N (Neutral). See “Shifting into N (Neutral)” under Four-Wheel Drive 0 241.

 

5. With the engine running, release the parking brake and verify that the transfer case is in N (Neutral) by shifting the transmission to D (Drive) and then to R (Reverse). There should be no movement while shifting the transmission.

 

6. Shift the transmission to D (Drive).

 

7. If equipped with an ignition key, turn the ignition to ACC/ACCESSORY.
If equipped with Keyless Access, turn the engine off.

Disregard the Shift to P (Park) DIC message.

 

See Ignition Positions (Keyless Access) 0 229 or Ignition Positions (Key Access) 0 228.

 

{Warning
To avoid death, serious injury, or property damage, before dinghy towing the vehicle, always disconnect and
secure the negative battery cable and cover the negative battery post and cable with a non-conductive material.

If the battery is left connected or the battery cable contacts the post, the Electric Parking Brake may activate during
towing, which could cause a crash.

 

8. Disconnect the negative (–) battery cable. See “Negative Battery Cable Disconnection” in Battery - North America 0 341.

 

9. Shift the transmission to P (Park).

 

Caution
If the steering column is locked, vehicle damage may occur.

 

10. Move the steering wheel to make sure the steering column is unlocked.

 

11. If the vehicle has an ignition key, keep it in the towed vehicle in ACC/ACCESSORY to prevent the steering column from locking.

If the vehicle is equipped with Keyless Access, keep the RKE transmitter outside of the vehicle and manually lock
the doors.

Access the vehicle by using the key in the door lock.

[TxTruckMan]

Wow. That’s overly complicated. GM needs to simplify that process for people who tow their vehicles.

[Gangly]

There are also specifics as to which variants can be dinghy towed.  If I remember correctly, 2WD and 4X4 vehicles are not supposed to be dinghy towed, only 4WD with 2 speed transfer cases.

[redwngr]

3 hours ago, Gangly said:

There are also specifics as to which variants can be dinghy towed.  If I remember correctly, 2WD and 4X4 vehicles are not supposed to be dinghy towed, only 4WD with 2 speed transfer cases.

Your memory is correct.

 

Of course 'dolly' towing is an option for 2wd and single speed transfer case trucks.