Purchased P3 w/Tekonsha factory harness. Installation is a breeze.

The problem I'm having is setting the brake power voltage and the activating the manual override. I started at 6.0 volts @ 25mph, then activated the override. No trailer braking. The braking with the voltage maxed at 13,6 volts(or maxed out) isn't very good and still won't lock up my trailer brakes. The brakes work ok with boost setting on 2, but something isn't right. Any ideas!

Truck w/ATV's and trailer are in my garage.

Did the trailer work with a different controller? When you have it set to maximum what is the current and voltage readings on the P3 display when manually activated? At 12 volts you should have about 12 amps.

I'll hook up the truck and take a look in the morning. I replaced an old tekonsha controller. With the old controller, the brakes would either fade w/braking or were very harsh and jerky. Had to adjust old controller just about every time I pulled the trailer. Maybe it's the trtailer and not the controllers as I thought. Wouldn't know were to start in trouble shooting any of this, but I'll get some voltage,amperage numbers of the P3. Thanks

To cover the basics first, make sure the controller is set to the correct type of trailer (single or duel axle,goosneck or fifth wheel double or triple axle). This will have an affect on braking performance for these controllers

Hooked the truck to my trailer this morning. The P3 is set-up at a max voltage of 12.8. The trouble shooting menu gave me these results:

Battery voltage:14.06 Volts
Stoplight:13.02 volts
Output Voltage:3.40
Output current:3.00 amps

When apllying the brakes I received 3.3 volts to the trailer according to the P3. P3 is set-up for electric brakes with no other options. Any Ideas..

Hooked the truck to my trailer this morning. The P3 is set-up at a max voltage of 12.8. The trouble shooting menu gave me these results:

Battery voltage:14.06 Volts
Stoplight:13.02 volts
Output Voltage:3.40
Output current:3.00 amps

When apllying the brakes I received 3.3 volts to the trailer according to the P3. P3 is set-up for electric brakes with no other options. Any Ideas..
If you are set at B3 that is about what you should expect. If you move the manual lever to full you should get about 12.8 volts and 11.5 amps.
When a P3 is set up correct you should not feel the trailer during a normal braking event. That is the trailer should not push the truck nor pull on the truck. With mine set at B1 I almost never can tell the trailer is there during normal braking.
When they say set it to just lock the brakes they mean use the manual lever to full travel. Some trailers will not lock the brakes if they are fully loaded.
My 11,000 lb 5th wheel only requires 6 volts to lock the brakes. I run with it set at 5.8 volts and B1 on the highway. I do not use any boost in a campground when backing and setting up trailer.

Sometimes it is difficult to detect locking brakes on asphalt unless you go back and look for the skid marks or have someone along side watching the tires.

My trailer weighs about 7500-8000 lbs loaded. The P3 is set @ 12.8 volts with no boost and will not lock the trailer brakes. It does slow the trailer with manual activation, but not as it should or like other controllers I've had in the past. Running highway speeds of 55-70 mph. I have to run B2 in order to have good trailer braking, but it is jerky, not smooth at all. There's really not any difference between the P3 and previous cheaper controllers. That's why I'm wondering if it could be something in my truck harness or the trailer wiring.

Have you adjusted the brakes on the trailer? Trailer brakes for the most part are not "self adjusting". If brake shoe clearance to drum is excessive -trailer is not going to stop good at any controller setting....

I adjust my trailer brakes before any trip of significant length.

My 14K fifth wheel will not easily lock up the brakes on pavement when fully loaded doing the 25 mph adjustment procedure for a Prodigy/P2/P3 controller unless Boost and gain are set pretty high. My trailer brake wiring is 10 gauge from RV Plug to brake magnet leads with crimp/solder connectors. No resistance issues in the wiring!!!! You might have wiring resistance issues in your trailer .... mine did from the factory.

Thanks trailwhale...I looked at the wiring. Might be 14ga. w/ crimp connects, Not a real clean job either. I'll do some rersearch on how to re-wire the trailer.

if your trailer jerks it sounds like one or more drum in out of shape and it might need new brakes and some new drums.