Car Trailer Question: Loss of Magnetic Ground

If they are magnetic brakes (which is usually the case with small trailers) the ground is the wire opposite the hot lead on the brake coil. It should have a clean solid bonding to the chassis. It may just need a good cleaning or new lug to bare metal. Some have an auxillary ground that is attached directly to the towing vehicle. If that is not the case, it could be a bad connection in your connecting plug. Try jumping out the coil ground (the one to the chassis) directly to the trailer. If the warning doesn't go out try touching it to the vehicle and see if it goes out. This may tell you whether it's the coil ground or the trailer jack. You may have to check each coil to find out which one is giving you problems.

Voltage to the coil is adjusted by applying your brakes. Sometimes just the emergency brakes will do.

Those would be called electric brakes.....right?

YEP

Hello, Like one has said you could have a ground pin problem on the plug. But some systems relay also on the ground through the hitch and ball and that can become intermittent due to corrosion.

The brakes work just like on the vehicle except using electrical coil to move a rod or lever like a solenoid. The higher the voltage the more force exerted.

Good luck metalSmiths's

ps. found this on the web brake controller and trailer troubleshooting.

Greetings at 5:33AM and Happy Thanksgiving.

I have had two pickups equipped with electric brake controls.

I like to pick the brains of people who are in the know so I asked a lot of questions of the installer. Hey I was paying for it and wanted to know as much as I could.

We finally got to problems. The installer/owner of the shop said that most of the problems happen when the controls are not tapped into the right point in the brake circuit. This can cause weird problems and even some fatal problems to the vehicle.

If this was done by a professional shop you are probably okay. If not this may be part of your problem.

The basic grounding can be checked by adding a battery jumper cable ground between the trailer and the vehicle. If the problem goes away you may have a floating ground which can be a high resistance open in the ground wire. Use a multimeter and check the connectors on the vehicle and then on the trailer for problems.

If that is the case take apart your connector and clean the connections.

You can always solder the connections into the connector which will eliminate a lot of problems like corrosion and loose wires.

With a car I always wired my bround directly to the engine block where the Battery ground was connected.

For trucks a frame ground works fine with their ground clearance.