Weak Braking w/ Tekonsha P3

OUTPUT VOLTAGE
No braking -- 0 V
Brake pedal fully depressed -- 3.2 V
Manual lever pushed fully to the left -- 12.1 V

OUTPUT CURRENT
No braking -- 0 A
Brake pedal fully depressed -- 1.5 A
Manual lever pushed fully to the left -- 10.0 A

A typical electric brake will draw about 3 A at 12 V. If you have four brakes, then 10 A is not far off from a theoretical 12 A. This implies that the controller, tow vehicle wiring, trailer connector, trailer wiring, and brake wires are all fine.
If the wires were bad, the current (amps) would be less.
If the connector was corroded, the current would be less.
If a brake wire was damaged, or a brake coil had failed, the current would be less.
That pretty much leaves just the brake mechanicals as the culprit. It could be brake adjustment, or a corroded pivot, or coils that are stuck too far away from the drum. Of these, adjustment is the most probable. It's possible there is a problem with the electric part, but if your controller readings are to be believed, I would sure start with the mechanical parts.

A very common failure with electric brakes is the wires to the magnet go bad and/or break off partially or completely.

Brake parts moving and rubbing wires or corrosion or just plain wear can cause it. The wires are often stiff and don't like that.

You can also clean the inside of the hub- the large flat round area- to which the magnet attached when charged. The hub then turns forwards and causes the brake lever to move, activating the brakes inside the drum.

If the inside of the drums are rusty, crusty, greasy, etc, the magnets can slip, resulting in the brakes not activating properly.

Also check to make sure the lining hasn't come partially or fully off the metal part of the brake pad. When trailer brakes sit for a while (ie over winter), they and the rivets or glue (yes, some don't use rivets only crappy glue :S ) can deteriorate.

Another thing.

MAKE SURE you used the proper wiring for your connector. I've seen two DIFFERENT diagrams!

You could also have a bad breakaway switch or battery connection to the switch, which can do strange things to your braking.

Tip: Using a 12v battery and a couple pieces of wire with the ends bare can be used to test your trailer wiring directly, using your trailer's connector, sans vehicle and controller.

It's already been mentioned to check your brake adjustments. The adjusters tend to rust on both manual and auto adjusting setups.

Hope this helps.

Put a magnet next to each hub and check for deflection at each hub when the brakes are applied.

Ron W.

Thanks for the responses. The brakes were properly adjusted during the 2012 season and prior. During that period I was able to lock up the trailer brakes on current and past trailers using the manual lever. Earlier today when I was taking my readings, I did see voltage changes when I changed the boost setting, but based on the power settings having already been set near the highest, I don't believe they can be adjusted upward enough to get to the point of adequate braking. The contacts on both sides of the 7-pin connector are clean. I just now tied the manual lever in the activated position with a string (I don't have a helper today) and listened to the wheels. I couldn't hear anything. Then I pressed my ear against each side wall and heard a buzz from each of the four, but I suspect the buzz could be getting transmitted through the scissor-type chocks. I guess I'll remove the chocks and try that again when it quits raining here. Any additional comments will be appreciated. Thanks again.

It will not matter what controller you use none will output much more than 12 volts. My trailer with a P3 will draw about 12 amps when 12 volts is applied. Your current output seems low. I suspect there is a problem with the trailer brakes or a bad connection to one or more brake magnets. FYI my trailer brakes will lock solid at 7amps. In the past were you able to lock your trailer brakes? Try the breakaway switch with 7 way disconnected. Do the brakes lockup then? If not you have a trailer brake problem.

Double check and clean the connections especially the trailer plug.
Some conductive grease on the plug after you get it good and clean on the truck and trailer sides can't hurt.
Good Luck, Mike
Sorry for the double post
THE BEAR types faster than my one finger :)

Have the trailer brakes been adjusted
Check the brake wiring connections for corrosion
If you turn the adjustment wheel for the brake controller do the voltage/Amps increase ? If not, then I would suspect something is wrong with the controller.