I've put a trailer brake controller in my '05 F150. It was in my '96 F150 and worked fine. Both have trailer tow pkg. towing the same utility 16' trailer. The problem is that now when I just barely touch the brake pedal, the trailer brakes come on way before the truck begins to stop or even slow down. When trailer is loaded it's not bad, but empty it's a bear even with controller set to .5 or 0. Any ideas?

 

Did you hard-wire the controller or use the underdash connector?

Steve

 

Used the underdash wiring. Both trucks used same plug. I just plugged into 05 harness. 05 already had 7pin plug in the back.

 

Hmmmm.........if the controller was working OK in the '96 and now shoots full 12vdc to the trailer with the gain at "0", I'm wondering if the activation wire from the cold side of the brake light switch is shorted into the output (heavy blue) wire to the trailer.

Steve

 

I'll check the wiring, but it will be a while. Thanks for the help.

 

I forget it's not 72* and sunny everywhere - sorry!!!

Steve

 

Its not as much the weather as it is finding room and time in the shop.

 

Gotcha - let me know if we need to guess something else.

Steve

 

Do you by chance know what controller you have?

Steve

 

Not right off hand, but it was in my other truck and is used on the same trailer and worked just fine.

 

Identical installation in terms of position, so the controller is at the same angle in both installations? Is it a timed controller that ramps up according to time on the brake pedal or does it depend on the rate of slowing of the truck?

Most controllers have an adjustment on the right and left side controlling how aggressively it activates as well as how the maximum setting it reaches (unless you have something digital). I was wondering if somehow you inadvertently moved the the adjustment on the left side, although I have to admit I am puzzled by a lock up engagement with a 0 setting. Controllers are pretty robust. I have had this happen to me, but in every case, I was able to correct it by making adjustments on the controller. The one thing you know for sure is the controller is active as you do not have locked trailer brakes all of the time, only when stopping.

I suspect this is an issue of adjustment rather than a fault in the plug receptacle. If you stay stuck on this, I would encourage you to call the manufacturer. I know folks are often hestitant to do that, but the most basic rule I have when teching is any time I am stuck for more than 15 minutes I call tech support at the manufacturer. They may be able to point you in the right direction instantly.

If you get the name off the controller, I will be glad to try to sort this out with you.

Steve

 

I have done some checking. I'm getting 12v on two wires for the controller plug with the controller and trailer unplugged. One is the 12v supply TO the controller from the brake circuit like it should be. The other is the brake wire from the controller to the trailer. I';m getting full 12v on the brake wire at the trailer receptacle and the controller plug under the dash. Its a short or improper connection. The wiring and harness look factory. Were these harnesses dealer, aftermarket or factory installed. I haven't traced the wires yet.

 

The under-dash brake controller plug is factory installed with the tow package. Are you the original owner of that '05 150?

Steve

 

I know that on my '07 the brake light comes on with only the slightest touch of the pedal (maybe 1/4" movement) whereas on older vehicles it may require a good couple of inches of travel. This would make the trailer module start to ramp in earlier. Just a suggestion.

 

First, thanks for all the help from everyone. I found and fixed the problem. Someone before i got the truck put a jumper wire from the brake signal wire to the controller output wire. They did this in the pigtail from the main harness to the controller plug and retaped with electric tape. The tape job was almost a factory looking job but not quite, I barely found it. They were contolling the trailer brakes off the brake light cicuit. I was lucky the wiring wasn't fried. Thanks again.