Originally Posted by jestew3
I used the Tekonsha P3 which I bought on Amazaon. I have one of these that I use in my Excursion and have had no issues with it at all. As for the blue wires, I just stripped one back and connected it to the 12V (Red) and used my volt meter on pin 2 to make sure I had the right one. I was lucky and guessed right the first time. I would go look for you, but the rig is in for warranty work.
I too used the Tekonsha P3. I used the Blue wire with the label "A" on it. I had to check like jestew3 with a meter to make sure I had the correct wire, but I believe in the end, both of us ended up using the one with a label of "A" or "LT A" on it.
I have towed my race trailer a couple times now. It's a 32' triple axle box trailer weighing in around 13,000#. I know I am over loaded, but our RV is pretty empty and I keep our tanks empty to try to help the GCWR. On steep incline hills I have to kick off the Overdrive with the switch under the radio and that really helps keep a head of steam on the hills. Otherwise, it does really well even over loaded.
The OD On/Off switch is in a terrible location (mine is on the far right side of the dash) so the next time I have my dash apart, I am going to switch it's location with the heated mirrors switch, which is far more accessible. Stole that idea from RobbyR.
BTW, love the P3 controller. Works very well for my application. I mounted it to the bottom side of the driver's side cup holder. Out of the way of my legs and feet, but I can still easily reach and see it for adjustments. Some have mentioned putting it in the ash tray location, but that was just a little too far away for my liking. I use the brake controller a lot while towing my heavy trailer. Trailer brakes are cheap and easy to replace compared to those on the Seneca. Although I must say, the exhaust brake on the Seneca makes slowing down a dream compared to my pick up truck!