How To Power An Auxiliary Braking System In A 2026 Buick Encore GX When The Battery Is Disconnected

Updated 11/25/2025 | Published 11/02/2025

Products Featured in This Question

Brake Buddy Select 3 Portable Flat Tow Brake System - Proportional

(314)

$1488.91

Roadmaster 4-Diode Universal Wiring Kit for Towed Vehicles - 7-Way to 6-Way Coiled Adapter Cord

(3188)

$175.27

Roadmaster Battery Charge Line Kit for Towed Vehicles

(1203)

$42.86

Roadmaster Battery Charge Line Kit for Motorhomes

(140)

$67.45

Roadmaster Battery Disconnect for Towed Vehicle w/ Flat Tow Brake System - Gas Only

(372)

$209.56

12 Volt Outlet Kit, 20 amps

(331)

$40.45

Roadmaster Stop Light Switch Kit

(623)

$44.30

Question:

I intend to flat tow. My toad requires the negative battery terminal be disconnected while towing. How can I power an auxiliary braking system on the toad while the battery is disconnected?

asked by: Kirk R

Expert Reply:

Hi Kirk!

To get a braking system working on your 2026 Buick Encore GX, you will need to start with something like the Roadmaster 4-Diode Universal Wiring Kit for Towed Vehicles - 7-Way to 6-Way Coiled Adapter Cord # RM-15267, if you do not already have that. From there, you will need the following parts (they are all Roadmaster as I think they make the best wiring components for flat towing):

Roadmaster Battery Disconnect for Towed Vehicle w/ Flat Tow Brake System # RM-766
Roadmaster Battery Charge Line Kit for Towed Vehicles # RM-156-25
Roadmaster Battery Charge Line Kit for Motorhomes # RM-156-75 (will not need if your motorhome already has a charge line - check position 4 on the 7-way on your motorhome (see attached image))
Roadmaster 12 Volt Outlet Kit, 20 amps # RM-9332

The disconnect kit will disconnect your battery and the towed vehicle charge line will keep your battery from being drained. You may need the motorhome charge line may not be needed if your 7-way has an active charge port, but if it isn't active when your motorhome is on, definitely grab it. The 12 volt outlet kit will them be wired directly to your battery and that will power a portable braking system. A permanent braking system will not need this as it will be wired directly to the battery.

Whichever braking system you go with, you will also need the Roadmaster Stop Light Switch Kit # RM62FR. This activates your motorhome's brake-monitoring system whenever brake pedal in in your Encore GX is applied. This ensures the supplemental braking system is functioning properly.

On that note, do you already have a braking system or have one picked out?

expert reply by: Lazer S

Charge Line Port On 7-Way
(click to enlarge)

Kirk R.

11/5/2025

The problem is the Charge Line Kit for Towed Vehicles # RM-156-25 requires the dinghy battery to be grounded and the Buick Encore manual specifically says the battery needs to be ungrounded when towing.

Lazer S.

11/6/2025

@KirkR I wish GM would have some kind of caveat in that section of the owner's manual. Yes, you want to disconnect the negative first as this will keep the positive from shorting if the frame is touched when unhooking it. The charge line does need a good ground so even though the manual says to disconnect the negative, I would still install the disconnect on the positive terminal. With a dedicated disconnect device, there is basically no chance of that positive shorting out on anything. If you were just unbolting and taking it off, there would be a higher chance of that, so definitely get the battery disconnect.

Kirk R.

11/12/2025

@LazerS The problem with using a battery disconnect on the Buick Encore GX is a mechanical one. The battery is covered by a metal plate that attaches to the positive battery terminal and a dozen battery cables connect to the plate. See attached picture. Looks like it will be difficult to separate the plate and relocate it to allow battery cables to be attached to the battery positive post and to the plate in order to connect the battery disconnect equipment. Have you dealt with this issue before?

Lazer S.

11/18/2025

@KirkR I got you picture and I see what you mean. They are making things way too complicated these days (insert heavy sigh here). You could try foregoing the charge lines and following the owner's manual by using the negative terminal for the disconnect, but I can't say with 100% certainty the braking system won't kill your battery. If you are going to be doing shorter trips, I think it will be fine. If you are taking longer trips though, I think I would start the Buick and run it for a little bit at every gas stop to make sure the battery is good.