Troubleshooting Low Voltage and SH Error Code on a Tekonsha Prodigy Trailer Brake Controller  

Question:

Expert Reply:

Because the output to the brakes is at 5 volts and you are getting the S.H error code from your Tekonsha Prodigy I believe that it could be 1 or a combination of several problems. First, the brake output power could be a result of too low of a setting on the brake controller. This can happen if you accidentally bumped the controller without knowing.

What you can do is go back and set up the brake controller as if it were the first time, making sure that it is installed in the correct positioning according to the installation details I have linked for you to view. If you are still getting only 5 volts, then other troubleshooting will be needed.

You will want to make sure that both the vehicle side and trailer side connectors are properly grounded to a bare metal surface and that the connector pins are free of any dirt and/or corrosion. A bad ground or corroded connector can cause a short which could cause a number of problems, including the 5.H error code.

With the brake controller re-positioned and set up again, and with clean, well-grounded connectors, test the output again at the trailer connector using a circuit tester like # PTW2993, if you do not already have one. If it is still not providing the correct voltage, then you know there is a problem on the vehicle side such as a loose wire, or there could be something wrong with the internal circuitry of the brake controller and it will need to be replaced.

You can also check that the brake magnets are in good shape. Start with a visual inspection of the magnets. If you see any of the windings coming through, then the magnets will need to be replaced. You will also want to check the magnet wiring. There will be 2 wires, one for ground and one for power. Make sure the ground wire is securely attached to a clean bare metal surface and that the power wire is intact.

If everything appears to be in order, you can move on to checking the brakes with a multimeter. 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

expert reply by: Michael H

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