Troubleshooting Agility Brake Controller Indicating No Trailer Connected with Trailer Connected
Updated 05/04/2011 | Published 05/03/2011
Question:
I have a 2002 Silverado 1500HD with the tow package. I purchased the Agility controller and the quick connect. I cant get the controller to show a trailer is connected. I have checked the black wire for power and the red wire for the stop switch, these are fine. If I hook a test light to the door ground and then to the blue wire the decimal point comes on and the test light activates when the override is hit. My trailer brake pin on the back of the truck shows 4.5 volts without pressing the override or stepping on the brake. Once I hit the override, the Volts to 0.0. I cant get the brakes to activate anyway, even when grounding to the door and the decimal point is on. The controller shows it is putting power to the brakes with the door ground, but nothing happens at the trailer. All the lights running, turns and brake lights work as they should. Any ideas?
asked by: YORK
Expert Reply:
First, we should make sure you have the correct wiring harness. You should be using # HM47795. This harness has the red pin for the stop light circuit unhooked from the plug. You will need to make sure it is placed in the correct spot. Check the port on the truck to determine where it needs to go. Using a circuit tester like # 40376, if needed, test the pins in the port until you find the one that is hot when you step on the brakes. Once you find it, place the pin in the corresponding spot in the connector and plug it in.
It could be a ground problem. If the brake controller ground is not good, it can cause any number of issues. The other possibilities are a bad ground at the vehicle side or trailer side connectors. You will need to check each place for a bad ground connection, loose or broken wires, and/or dirty and corroded connectors.
If everything checks out the possibility exists that the brake magnets on the trailer brakes could be bad or going bad. They too require a good ground connection. You can visually inspect the magnets first. If you see any of the windings in the magnet 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 a 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
