Can the Roadmaster Automatic Battery Disconnect Be Used on the Negative Side of the Battery

Updated 03/02/2022 | Published 03/01/2022

Products Featured in This Question

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

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$202.90

Deka Lead Quick-Disconnect Battery Terminal - Universal Polarity

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$29.19

Question:

Hi, my GMC Canyon manual states that the negative cable should be disconnected not the positive when towing. Does it RM-766 works on the nagative cable in the same set up of installation? plus the negative battery terminal is different from the positive, so how should it attach to the solenoid cable. Thanks

asked by: Aristides

Expert Reply:

The Roadmaster Automatic Battery Disconnect # RM-766 does need to be installed on the positive side of the battery, even on vehicles that state to disconnect the negative cable.

Roadmaster released a tech bulletin about this and the reason is because if you use the disconnect on the negative side you'll lose your towed vehicle's main ground to the chassis. This means that all of the accessories that need to operate on the toad must be grounded through the connection to the motorhome which is not going to be a good connection. The ground wire is too small of a gauge and the distance is too great to get a good ground.

So even though your manual states to disconnect the negative side you want to install the battery disconnect on the positive.

If this is something you are not comfortable with, you can use the Deka Lead Quick-Disconnect Battery Terminal # DW05312 as another option to disconnect the negative side. This would require you to open the hood each time to disconnect and reconnect your battery.

expert reply by: Scott S