Troubleshooting Poor Brake Performance and Low Brake Output Voltage

Question:

i have the draw tite activator 4 brake controller and it is sending power to the rear but at a constant 9 volts but will not adjust or engage the brakes hard enough to stop the trailer my truck is a 98 dodge 2500 4 wheel drive withe a 360 motor

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Expert Reply:

First thing I would check is the blue wire that is at the rear of your vehicle for voltage when you apply the brakes and when you slide the manual override of this controller. You could also try sliding the manual override a few times and adjusting the gain knob up and down to help clear the contact points.

I attached a link to the manufacturers instructions for your Draw-Tite Brake Controller, part # 5504, below for you to check out also.

If all this checks out it sounds like the problem is in the trailer somewhere. I would first check all the grounds of the trailer and make sure they are making solid corrosion-free connections.

The next thing to check would be the magnets in the brake assemblies. When these wear out can get poor brake performance.

If the magnets show abnormal wear or if you can see the windings beginning to show through the friction surface of the magnet then they will need to be replaced.

To further test your magnets, first make sure the trailer is not connected when performing this test. If the trailer is connected, you run the risk of shorting out the brake controller or various other electrical components.

To test the brake magnets with an ammeter, connect the ammeter between the positive battery terminal of a separate battery and one of the magnet wires. Then, connect the other magnet wire to the negative battery terminal. Check the amperage, if the amperage is greater than the specified amount in the chart below, replace the magnet. If the reading is less than the specified amount, then the leads are bad and the magnet should be replaced.

Electromagnet Specifications:

7 inch Diameter Brake Drum:
Max Amps at 9-10.5 Volts
2 Brakes 4.7-5.6
4 Brakes 9.5-11
6 Brakes 14.3-16

Max Amps at 12-13 Volts
2 Brakes 6.3-6.8
4 Brakes 12.6-13.7
6 Brakes 19.0-20.6

10 and 12 Inch Brake Drums
Max Amps at 9-10.5 Volts
2 Brakes 5.6-6.6
4 Brakes 11.3-13.3
6 Brakes 17.0-20.0

Max Amps at 12-13 Volts
2 Brakes 7.5-8.2
4 Brakes 15.0-16.3
6 Brakes 22.6-24.5

Next, disconnect the negative wire from the brake magnet wire and connect it to the base, housing, of the brake magnet. If there is any amperage, the magnet is shorted and will need to be replaced.

Finally, using an ohmmeter, check the resistance between the brake magnet wires. If the resistance is not within the specified range below, the magnet will need to be replaced.

7 inch brake magnet resistance should be 3.8-4.0 Ohms
10 and 12 inch brake magnets resistance should be 3.2-3.5 Ohms

expert reply by:
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Jameson C

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