Forum Discussion

RamTX's avatar
RamTX
Explorer
Jul 10, 2017

Voltage Drop Across New Breakaway Switch

I recently replaced my existing breakaway switch with a new one manufactured by Hopkins. In testing it, I could not hear the brakes actuate when the switch was energized. I checked my voltage for the on-board rv battery and measured the voltage as 12.48v. I then measured across the switch and measured the voltage as 10.63v. The wires on the Hopkins switch are 18 gauge, but they are short wires. Anyone have any experience with voltage drops and actuating brakes on the trailer thru the breakaway witch? Thanks.
  • jonrjen's avatar
    jonrjen
    Explorer
    Jul 15, 2017
    Why did you replace the break away switch with a replacement? Was there an issue with the original? Did you check the voltage reading on it before replacing it?

    Did you wire the new switch directly into the junction box and tie it into the wire harness or cut the old wire leads and tap into the old wire harness of the original break away switch?

    Have you check for a voltage reading at the wires in the junction box located at the hitch?
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jul 10, 2017
    Allworth wrote:
    You might try measuring from the input wire of the switch to a chassis ground. You should get battery voltage.

    Then (with the pin in place) measure output wire of the switch to ground and it should be zero.

    Pull the pin and output wire to ground should be same as battery voltage. i.e. there should be NO internal loss in the switch. If there is, the switch is defective.

    A


    This^^^^^^

    The breakaway switch should pass FULL battery voltage.
    DOT requirement is emergency brake system supply FULL battery voltage for 15 minutes
  • Allworth's avatar
    Allworth
    Explorer II
    Jul 10, 2017
    You might try measuring from the input wire of the switch to a chassis ground. You should get battery voltage.

    Then (with the pin in place) measure output wire of the switch to ground and it should be zero.

    Pull the pin and output wire to ground should be same as battery voltage. i.e. there should be NO internal loss in the switch. If there is, the switch is defective.

    A

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