Can The Negative Cable For The Invisibrake Be Attached To Chassis Ground Instead Of The Battery

Updated 08/01/2025 | Published 06/28/2023

Question:

Invisibrake 8700 Roadmaster installed on 2023 Chevy Silverado. Power Wire page 12 of manual says, connect to battery, or black can be grounded to chassis. But then it says, If battery is disconnected, cables must be connected to the battery. On the Chevy, only the negative is disconnected. So can the black wire from the Roadmaster be grounded to the chassis or do I need to disconnect the negative, but then reconnect only the black wire from the roadmaster to the negative battery terminal?

asked by: Michael J

Expert Reply:

When you disconnect the battery it's to prevent systems inside the vehicle from activating. The Roadmaster InvisiBrake Supplemental Braking System # RM-8700 will still need to be wired directly to the battery for power. The only time you should use chassis ground is if the negative battery terminal can not accept aftermarket accessories. You'll disconnect the negative battery cable like your vehicle's manual states but leave the Invisibrake cable attached to the terminal.

expert reply by: Kevin C

Jim A.

7/26/2025

How about the white wire of the four wire harness attached to the Invisbrake that goes up to the RV 7 wire plug and back to the tail lights. Can that be grounded to chassis per the install diagram? Will it back feed through the Invisbrake back to the battery post? Is it doing anything when attached to the chassis when the the battery ground is disconnected? CAUTION Failure to establish good ground connections WILL CAUSE non-warranty electrical damage to InvisiBrake. Other consequential non-warranty damage may also occur. A good ground connection MUST EXIST… • …between the towed vehicle and motorhome; ""• …between InvisiBrake and the towed vehicle and"" • …between InvisiBrake and the motorhome. If the towed vehicle has been wired for towing, check to make certain a good ground exists between the towed vehicle and the motorhome; refer to the illustrations below and to the complete wiring schematic near the beginning of these instructions for InvisiBrake ground wire connections.

Lazer S.

7/28/2025

@JimA Hi Jim! The ground Kevin is referring to is the one that is included in the harness that also has the break away switch. For the rest of the grounds (the white wires that are connected to the 7-Way), you will want to ground those directly to the chassis. When properly and securely attached to clean/bare metal, there should be no back feeding. You will still be getting a ground connection when the battery ground is disconnected, but definitely not as good of one. This can cause issues, so you really want that black wire attached to the negative terminal on your battery is you can. If your vehicle does not allow for this, you can use the chassis. Are you installing this on a Silverado or a different vehicle?

Jim A.

7/28/2025

@LazerS Thanks Lazer. I'm installing the 8700 on a 2021 GMC Canyon. My thought was to install the power wires to the battery side of a disconnect switch. Manual says disconnect negative side but might disconnect positive or maybe both. Since both power wires from the 8700 will still be hooked to the battery, I was worried that the negative would travel back through the black negative power wire, through the 8700, and then through the taillight white wire which will be grounded to the chassis. This could power things back up in the Canyon. If I use the ground from the RV to ground to the Canyon taillight white wire, Canyon chassis, and 8700 white white 4 wire "taillight" plug in theory the Yukon should be dead. Then the only common point between the black power negative wire and the white taillight ground wire would be internally in the 8700. I suppose I could check continuity between the 2 plug jacks ( black negative power wire and white 4 prong) on the 8700 before I install. Thanks again.

Lazer S.

7/31/2025

@JimA Man, you are thinking all the thoughts! With having multiple grounds for the InvisiBrake though, I don't think there will be any issues with power going back in to your Canyon. I will admit to not having installed one of these on a Canyon before, so double checking continuity is never a bad idea!