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Check voltage at each magnet should start out around 2 volts and go up to 12 volts fully applied.
To check just the controller you can test voltage coming out of trailer cord socket,, if its not varying voltage there its not going to be doing it at any wheels.
Then if it is there then go to each wheel and check.
Make sure brakes are adjusted page 13.
Once you adjust brakes they need to be synchronized with tow vehicle,, read page's 11 and 12 to accomplish this.
If you are getting proper voltage and all good grounds replace magnets.
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