There are several ways
To check electric brakes, some temporary supplies are required. Aside from just dragging the trailer down the road, static testing will check for braking action. To do a test, a battery must be placed at the tongue of the trailer, a 30 amp ampmeter, a 12volt dc test lite, and a couple number 12 gage test wires with aligator clips. The easy test...connect battery negative post to good frame ground or to trailer battery ground. Connect amp meter to trailer electric brake wire. Observe meter while making connection and note amps,.... should be about 15 amps. If amp reading is very low, one or more brake magnet coils are not working. To be assured all brakes are getting 12volts dc, use test lite at each wheel. Disconnect jumper from battery and remove meter. With a sngle wheel jacked off ground, have helper spin wheel and observe wheel stopping as power is applied to brake control wire..... Or just hook up to tow vehicle with correct brake controller......
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