What Would Cause Voltage Drop Between Front of Trailer and Brake Assemblies

Question:

I am working on trailer brakes on a 40ft gooseneck dual tandem axles l. I have 12 volts at the wires before the magnets tie in. When I plug in the wires to the magnets and it engages the brakes the volts will to 10 volts. Is this normal? Or should the stay at 12 volts? I am powering the brakes at the plug with a 12 volt battery. I have cleaned all grounds and connections. If the is not normal would I need to run bigger wire?

asked by: Derick K

Expert Reply:

Typically if there's a large voltage drop like you mentioned the issue is the longer run of wire not being a heavy enough gauge of wire. You'll need to use 10 gauge wire like 10-1-1 to make the run from the front of the trailer back to the assemblies and you'll see the voltage drop be much smaller.

expert reply by: Jameson C