Electric trailer brakes are essential to safely transporting loads. Regular inspection of
your brakes for wiring shorts or internal breaks within the brake magnets
themselves should ensure proper function and prevent potential problems from developing.
Multimeters are excellent tools for testing trailer brakes. Simply follow these steps to examine their functionality.
Amperage
Electric trailer brakes work by applying electrical current from a brake controller
directly to your trailer’s brake magnets, through an electrical current supplied from
the controller. If your trailer brakes aren’t functioning as they should be, it could be
that either its controller isn’t functioning as intended or its current isn’t reaching them.
Use a multimeter to conduct this test. First, set it to read resistance (Ohms). Place
one lead of the multimeter on the BLUE wire on your connector plug, while another
on black magnet wire – both should display amperage readings that should fall
within acceptable parameters based on your brake magnet size.
Checking electric trailer brakes is only one way of checking their condition, however.
Be wary of electric shock by following manufacturer recommendations regarding
maintenance and testing; additionally, regular comprehensive trailer inspections
should also be carried out to ensure all of your trailer systems remain in top shape.
Voltage
Electric brakes work by feeding current to the brake magnets from your trailer’s
controller panel. If your wheels aren’t spinning or stopping when you apply them
manually, either your controller is malfunctioning or its wires from it to the magnets
are broken or corroded – to test these wires use a multimeter that reads DC and AC
amps; connect its negative probe to battery terminal and its positive probe to any of
the magnet wires, placing one probe near each brake magnet wire and checking
that its reading falls within acceptable parameters depending on size of brake
breaker size of course!
Test your brake controller by cutting the blue wire that emerges from its connector
plug and connecting its red lead with each of the wires leading TO the brakes, not
INTO them (like this one). Your reading should conform with specifications given
above – be careful if exposing magnet wires directly to +12V for more than a few
seconds at a time as this can quickly lead to damage!
Resistance
Resistivity measures the resistance of an electric trailer brake against electricity
flow, typically measured using a multimeter. If this measurement falls outside the
suggested resistance ranges, this may indicate there is something amiss with either
its wiring or magnets that needs attention.
An effective way to test system resistance is to disconnect the trailer from its tow
vehicle and place one meter probe on each brake magnet wire. If readings remain
high, brake replacement may be required or it could signal a short circuit caused by
malfunctioning controllers or malfunctioning magnet coils.
One method for testing system resistance is measuring the current flowing from the
controller to brake magnets while running the engine of a tow vehicle. This can be
accomplished using a multimeter attached to blue wire coming from connector plug,
with another probe touching a brake magnet wire; once connected properly it
should show that current is flowing indicating an acceptable reading.
Short Circuit
There could be several reasons your trailer brakes may be nonfunctional, from
simple deposition on the drum area to issues with your controller and wires. A
multimeter can help detect internal short circuits in your circuit.
Attach one probe from your multimeter to the blue wire that connects from the
trailer pin plug to your brake magnet wires and apply current through your system;
connect another probe to an object such as a wrench for testing purposes and apply
current. Metal should stick, while your multimeter should read off an accurate amount of current.
Before connecting your multimeter to wires, be sure to disconnect all power sources
so as to prevent electric shock. Always read and follow the testing tips and safety
advice in its manual before using it. For additional assistance, consult with an expert
trailer specialist who can quickly identify and fix the issue.