Brake controller

Craigrrr · 12-10-2015, 09:10 PM

I have a Tekonsha Primus IQ brake controller, have not used it in a while, so today was the first time using in about a year guesstimate. I noticed that when I put on the brakes it does what it is suppose to do ...the voltage increases and the trailer stops, now here is the question. when I come to the stop, the controller goes down to zero then it goes back up to say 2.0 2.1 on the front of the controller. Does that mean my brake pedal is seeping in my tow vehicle causing that ? I don't remember if that's how it was a year ago with my other trailer. So if anyone has hooked theirs up recently and noticed that would you please let me know. Thanks

Craig

BrucePerens · 12-10-2015, 11:20 PM

I have a Tekonsha P3. It has an on-off sensor from the brake light switch and an internal inertial sensor that controls the degree to which it applies the brake. It appears that even after you release the brake pedal, the controller will continue to apply the brakes to the trailer until the inertial sensor stops sensing that the tow vehicle is decelerating.

The Grand Cherokee 2015 model has some odd braking software enhancements, perhaps they are interfering with it? It will hold on a grade by itself, it has software anti-sway, and if you release the gas pedal suddenly it will apply the brake slightly on its own, so that if you then do a panic stop the stop happens faster without any need to push past slack in the braking system.

I've also caught it oscillating once. Trailer brake application at highway speed caused the tongue to go up or down, which caused the tow vehicle front axle to go up or down, which the brake controller sensed as brake application and release and it correspondingly applied and released the trailer brake. Sort of like sway, but up and down. And it just kept oscillating until I manually applied the trailer brake. The weight distributing hitch and the odd passive rear leveling system in the Grand Cherokee might have been involved. I haven't pulled the trailer since, so I've had no time to investigate this yet. It might be that I have made the WDH too strong.

Shane826 · 12-10-2015, 11:24 PM

I have the Draw-Tite rebadged version of the Primus. I hope to set up my WDH tomorrow, I'll take a look.

However I'm pretty sure it's not your brake pedal "seeping". The brake pedal (brake light, actually) input is only to signal to the controller WHEN you are braking. The actual brake application is measured by an acceleration sensor. It detects deceleration and applies the trailer brakes accordingly, but only does so when it sees te brake light input.

I think the numbers have something to do with your boost settings. At the very least I'll look at the instruction manual for you tomorrow. Stay tuned...

**Kwantau** · 12-11-2015, 05:56 AM

I have a P3 on my Grand Cherokee now for 4 years and the 2.0-2.1 voltage you are seeing when you stop is a normal condition. The controller applies this as soon as you come to a complete stop and as long as you keep pressure on the TV brake pedal. In the instruction manual it explains this as a voltage to keep the trailer brakes applied. This would be important when you stopped on a hill by taking some of the trailer pushing you off your TV. Hopes this explains it well enough for you. Nothing to worry about.

scrubjaysnest · 12-11-2015, 06:58 AM

We have the P3 and it also shows the same. The Grande Cherokee has some fancy software but our 2005 left me in the middle of a 6 lane intersection when the wheel speed sensors failed and locked the brakes. The software has very poor sensor failure detection and rejection methods.

Craigrrr · 12-11-2015, 07:30 AM

Thanks guys, I was hoping it was normal. I just could not remember. Lol

Shane826 · 12-11-2015, 10:42 AM

Oh I misread. I thought you meant as you started rolling again it went back to 2.0... Yeah that's a holding brake. Normal.

Craigrrr · 12-11-2015, 10:50 AM

I was stuck in traffic yesterday on the way back from picking the tm up and thought man that magnet must be getting hot with the voltage being applied .
I was thinking terms of a solenoid being stuck on with voltage and getting hot. That was why I asked cause I just could not remember seeing it on that long, but traffic here gets worse everyday .