Can Roadmaster Automatic Battery Disconnect RM-766 Be Used On 2021 GMC Sierra 1500 Being Flat Towed?

Updated 07/26/2021 | Published 07/23/2021

Question:

The manual says discount the negative terminal. Will this work on the negative terminal? The video shows the positive.

asked by: David H

Expert Reply:

I reached out to my contact at Roadmaster, and the Roadmaster Automatic Battery Disconnect with Switch for Towed Vehicle w/ Supplemental Braking System # RM-766 can only be used on the positive terminal of the battery as that is what the polarity of the solenoid is designed for.

My contact mentioned that nearly every owner's manual mentions disconnecting the negative terminal, but using their disconnect and disconnecting the positive terminal accomplishes the same thing. This has been tested and will not cause any issues.

If you are dead set on disconnecting the negative terminal, you will need to use a manual disconnect that is rated for use on the negative terminal.

I included a video of the # RM-766 for you to take a look at.

expert reply by: Samuel C