Voltage at Brake Magnets is 8 Volts with Brake Controller Set to Maximum
Updated 07/16/2024 | Published 01/05/2014
Question:
i have a 2008 gmc 3500 dually trailer is only getting 8 volts at trailer brakes when brake is at max,,should it be getting 12 volts?
asked by: Donald C
Expert Reply:
It should be getting close to 12 volts if the power output is set to the maximum on the brake controller. Some brake controllers will not work properly if they are titled or turned to the side or if it has a leveler knob that is not level. Check those things first since they are the easiest.
First, sever the blue wire behind the the brake controller a few inches and use your meter to test the end coming from the brake controller. With the output set to the maximum it should read at least 12 volts when the manual override is applied. If it does not or it shows power without the manual override engaged then there is something wrong inside the controller and it will need to be replaced. If it checks out ok then reattach the blue wire.
Next you can check the brake output pin on the truck side 7-Way using a multimeter. At full power you should be seeing close to 12 volts. If it is 8 volts there as well then there is something causing the voltage to drop between the controller and the 7-Way. Check for loose connections, breaks in the wiring, and corrosion inside and outside of the connector.
If voltage is proper at the 7-Way then make sure the trailer side connector is clean and free of corrosion. Then make sure the main trailer connector ground is attached to a clean and corrosion free bare metal surface. Inspect the brake magnet power wires for any breaks in them. Also make sure the brake magnet ground wires are attached to a clean and corrosion free bare metal surface near the magnets.
Visually inspect the magnets and if you can see the windings coming through then they will need to be replaced. To further test the magnets you can follow the FAQ article I have linked.
Product Page this Question was Asked From
Dexter Electric Brake Assembly for 4 Bolt or 5 Bolt Flange - 12" - Left Hand - 6,000 lbs
- Accessories and Parts
- Trailer Brakes
- Electric Drum Brakes
- LH
- 6000 lbs
- Brake Assembly
- Manual Adjust
- 12 x 2 Inch Drum
- Dexter
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Pierre B.
7/16/2024
I have a proportional brake controler and I get 11 Volts out of my 7 pins connector brake pin , however I only meseure 8 Volts to my Travel trailer wheels (2) , may be wire resistance that I have been told ? Is this enough Voltage to get strong braking or should I get more . Thank you for your help!