Jim T.
6/28/2021
Hi. I have a 2009 Heartland Cyclone toy hauler with three axles. and tow it with a 2006 Volvo VNL630 tractor, and have recently noticed that the brakes are not working. The Volvo has an air/electric brake controller, which works. I have tested it with another trailer and a controller tester. On the trailer, I have measured the resistance between ground and the brake (blue) wire, and get 1.8 ohms. According to your chart, the resistance of a brake magnet should be between 3.0 and 3.8 ohms. Using 3.4 ohms, six of these in parallel should result in a resistance of about 0.567 ohm. 1.8 ohms would closely relate to only two brake magnets in parallel Applying trailer battery voltage (appx 13.4 volts) between ground and the brake wire, I measure about 10A +/-. Your chart shows that it should be between 22.6 and 24.5 amps, which would be more appropriate for a resistance of about 0.6 ohms. This too would almost relate to only two brake magnets in parallel (I=13.4 v/1.8 ohm = 7.45 A). Question is, is it possible to have four brake magnets go bad? Does my analysis make sense, or am I missing something? Thank you for your help.
Jim
12/2/2021
Some brake controllers do not put out voltage unless the vehicle is moving above a certain speed. This can be worked around by using the manual activation bar.