Brake controller problem

[Dant]

How did THIS happen?

I had a trailer outfit install the complete wiring and brake controller (Tekonsha Primus IQ) on my 2010 Toyota Tacoma 4 cyl. regular cab that had zero tow wiring.

Everything seemed fine for a few miles, no trailer hooked up, when the Tacoma's brakes started applying. At first I thought I'd shifted into the wrong gear, it was as if I was in 4th when I should be in 2d.

ABS and skid control lights came on. Turned off engine, waited. Turned ignition on again, ABS and skid lights still on.

When I pulled over, the smell of hot brakes was unmistakeable. Installer came over and
disconnected the system completely. No problem now, except the brakes have been damaged to some degree. There is some drag, very slight, just enough that the truck does not roll completely free.

The installer is mystified as well as embarrassed. He says he's installed dozens of these on new Tacomas. He's offered to replace the controller with a '$500' controller that operates by remote control so it bypasses the wiring.

How can the controller possibly activate the tow vehicle brakes?
Installer wrote:

"Just ordered the Prodigy RF for you. It will be here tuesday and we will install and test it tuesday afternoon. This new controller just plugs into the 12v accessory plug(cig lighter) and thats it on the truck. When you get your trailer we'll mount the brake control box on the trailer. Just 2 screws and the trailer plugs into it and thats it. Prodigy RF made by tekonsha is the manufacturer if you want to look it up. Its a remote controlled unit with accelerometers built in. $500 unit but we are not going to charge you at all. Sorry about the issues. We will for sure get them all worked out for you. "

[vreihen]

How can the controller possibly activate the two vehicle brakes?

I don't know specifically about Toyota, but other traction control systems that I've seen work by electronically applying the brakes on a skidding wheel. If there is a brake pedal position sensor in your truck and it uses +5 volts as a reference signal, the installer may have tapped the pedal position sensor wire instead of the brake light switch wire, sending +12V (or grounding) a signal that the computer wasn't expecting. Your ABS controller may be toast at this point. Pure speculation, of course. Given Toyota's recent history of runaway fly-by-wire throttle pedals, I wonder if the NHTSA shouldn't have a look at your truck to see if a bad input confused the ABS computer?

Their offer of the Prodigy RF was generous, with two caveats. It still needs +12V to power the box mounted to the trailer tongue, and you won't be able to tow any other trailer with brakes using your truck since the Prodigy RF is mounted on your trailer and not in the truck.....

[Dant]

Thanks. I'll forward your post to the installer.