SH Code Displayed on the P2 Brake Controller When Trailer Brakes are Applied with 2005 F-150 Truck

Question:

i have a tekonsha p2 the trailer brakes seem to work but the controller still says SH and that i have a overload any help 2005 f150 with towing pkg

asked by: David

Expert Reply:

Since the brake controller is only showing the SH (Short) code when the trailer is connected, it sounds as if there is an issue with the trailer wiring or trailer brake magnets. I would start with the easiest fixes first and then work my way to the most difficult troubleshooting measures.

First, check the trailer connector. Open it up and look inside the connector. If you find a loose wire shorting to the trailer brake feed or corrosion inside the connector, this could be the issue. Fix any mis-wiring, see link to trailer connector diagrams, and clean out the connector if any corrosion is found. Some dielectric grease, # 11755, will help prevent corrosion and would be a good idea to use on the connections while you have the connector open. If you determine that you need a new connector, the Pollack 7-Way RV connector, # PK12706, would most likely be the correct choice for your truck and trailer. While you are at it, it would be a good idea to check the vehicle side connector also.

Next, check the ground wire at the trailer tongue and make sure it is grounded properly to a rust, paint and primer free portion of the trailer frame. Also, make sure one wire from each brake magnet is grounded properly either to the ground wire from the trailer connector or to the trailer frame.

Next, check the brake feed power wire all the way back to the brake magnet connections. If the wire is pinched frayed or broken and contacting the trailer frame or another wire, correct any of these issues.

If the solution to the problem is still not found, check the brake magnets themselves for wear. This will require removing the trailer hub and drum, and visually inspecting the trailer brake magnets. If you see the magnet windings coming through the face of the magnet or abnormal wear, the magnet is shorted and will need to be replaced.

If there is no apparent damage, the magnet can be tested, see brake magnet testing link, by connecting the base of the brake magnet to the negative post of a 12 volt battery and connecting one of the brake magnet wires to the negative lead of a multimeter, # PT89ZR. Connect the positive lead of the multimeter to the positive battery terminal. If there is any amperage the magnet is shorted and will need to be replaced.

While you have the trailer hubs off of the axle, now would be an excellent opportunity for inspection and greasing of the bearings and checking out the brakes on the trailer.