Troubleshooting Tekonsha P3 90195 Brake Controller Not Reading Trailer Brakes

Question

Question:

Hi, I have a 95 F350 7.3. With the P3 brake controller it has worked flawlessly for years, last week I hooked up my trailer started driving and I got the message trailer disconnected.. I pulled over checked my connections got back in and still said the same thing, I chalked it up as the trailer side... fast forward I hooked the trailer up to another truck and that brake controller was working fine I then started probing around and tested the wires and socket at the back of the truck newer style Ford socket contacts were dirty on the back side I pulled it apart cleaned it hooked a pig talk trailer plug in rubber banded The brake slider on and it was showing on my Power probe that it was receiving a signal. Thought I fixed this issue since before I slid the slider and tested and got nothing.. hooked it up today and same thing the brake controller does not recognize the trailer lights everything else works all fuses are good? Can the controller be bad? My next step is to put an old controller in and see if it sees the trailer.

asked by: Jason

0

Expert Reply:

A brake controller will send our a small amount of test voltage that can sense the resistance from the brake magnets and determine if a trailer is plugged in. When the brake controller fails to 'read' the trailer, it's typically caused by one of three things:

• A damaged or corroded trailer connector on the truck can prevent the signal described above from
reaching the trailer brake magnets. If you see any green or white corrosion on the pins of the connector,
there's a good possibility that the corrosion has spread to the interior of the connector where the wires
connect to the terminals which prevents the signal from getting through. You'll want to clean or replace the
trailer connector as needed. Part # PK11893 would work well as a replacement.

• What's mentioned above can also hold true for the connector on the trailer itself. Clean/replace as
necessary. If a 60 inch whip would work for you, the # 277-000141 7-way whip/junction box would work well. A
junction box provides protected location to make all the wiring connections. The box is weatherproof, and
would make for a tidy and professional install. Be sure to look closely at these wire color codes as what's
on your trailer could be different. White-ground, Black-12V power supply, Green-taillights, Brown-
Right turn/brake lamps, Blue-brake controller output voltage, Yellow-reverse lamps and Red-left turn/brake
lamp.

• Worn trailer magnets. If the face of the magnet that rides against the inside armature surface of the
hub/drum is worn to the point where the copper wiring encased in the magnet is showing through, it can
prevent the brake controller from reading the trailer. In most cases you can replace the magnets
themselves if necessary, but we typically recommend simply replacing the brake assembly itself as that will
provide you with all-new brake pads and springs so you'll have reliable braking.

I've linked to a brake controller troubleshooting article and to an install video for the whip/junction box I mentioned above.