Flat Towing 2017 GMC 2500 HD 4 x 4

[jimstringer]

Need GM Service Bulletins and all other available information on flat towing my 2017 GMC 2500 HD 4x4. Do I have to disconnect both batteries? Is there another way that precludes having to disconnect the batteries without damaging the electrical system, running the battery/batteries down, or having to reprogram all electrical accessories, (radio, seats, etc.)

 

All I have found is the attached service bulletin on 2014 Sierra 1500 4x4.

[O_J_Simpson]

You want to do it right you need to disconnect both drive shafts.

[newdude]

Instructions are right in the owners manual. Might want to give it a quick read...

 

Four-Wheel-Drive Vehicles

 

Only dinghy tow four-wheel-drive vehicles with a two-speed transfer case that have an N (Neutral) and a Four-Wheel Drive Low (4 (n) setting.

 

Warning: Shifting a four-wheel-drive vehicle's transfer case into N (Neutral) can cause the vehicle to roll even if the transmission is in P (Park). You or others could be injured. Set the parking brake before shifting the transfer case to N (Neutral).

To dinghy tow:

 

Caution: Failure to disconnect the negative battery cable or to have it contact the terminals can cause damage to the vehicle.

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

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. Check that the vehicle is in N (Neutral) by shifting the transmission to R (Reverse) and then to D (Drive). There should be no movement of the vehicle while shifting.
5. Turn the engine off.
6. Disconnect the negative battery cable at the battery and secure the nut and bolt. Cover the negative battery post with a non-conductive material to prevent any contact with the negative battery terminal.
7. Shift the transmission to P (Park).
8. Move the steering wheel to make sure the steering column is unlocked.
9. With a foot on the brake pedal, release the parking brake. Keep the ignition key in the towed vehicle in ACC/ACCESSORY to prevent the steering column from locking.

Disconnecting the Towed Vehicle

Before disconnecting the towed vehicle:

 

1. Park on a level surface.
2. Set the parking brake, then shift the transmission to P (Park), and turn the ignition key off.
3. Connect the battery.
4. Apply the brake pedal.
5. Turn the ignition on with the engine off. Shift the transfer case out of N (Neutral) to Two-Wheel Drive High. See “Shifting out of N (Neutral)” under Four-Wheel Drive. See your dealer if the transfer case cannot be shifted out of N (Neutral).
6. Check that the vehicle is in Two-Wheel Drive High by shifting the transmission to R (Reverse) and then to D (Drive). There should be movement of the vehicle while shifting.
7. Shift the transmission to P (Park) and turn off the ignition.
8. Disconnect the vehicle from the tow vehicle.
9. Release the parking brake.
10. Reset any lost presets.

    The outside temperature display will default to 0 °C (32 °F) but will reset with normal usage.

Edited August 11, 2017 by 15HDriver

[D410VE]

#7 on hooking up says shift to Park. #2 on disconnect says shift into park. While towing should the transmission be in Park or Neutral?