Compatability of Tekonsha P3 with Hydraulic Over Electric Brakes

Expert Reply:

There are 3 possible causes for the display reading - No Trailer Connected - on the Tekonsha P-3, Item # 90195, when the trailer is connected. The first cause could be that you do not have the P-3 set up in the Hydraulic mode. On page 4 the instructions (see link) explain how to set the brake type, electric or hydraulic. The second possibility is that you do not have a constant 12 volt supply ran to the hydraulic pump. If you do not have the power ran or connected properly the brakes will work when applied but will not have the power to operate the pump fully. The third problem is less likely but sometimes it is necessary to wire the ground wire from the hydraulic pump directly to the ground wire in the 7-way connector to get a strong enough ground.

expert reply by: Bob G