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Firstly, I apologize if this has been covered, but I can’t find an answer.
The car is a 2011 Cayenne GTS, without the tow option.
I have installed the VW adapter plug, and am using a Prodigy P3 electric brake controller, I also included the relay.
The Prodigy is working, and I can get trailer braking if I use the override, but I am not getting a braking signal from the car. I am not using a Porsche trailer brake control module.
i have monitored the brake signal coming from the car, and I am not seeing any change when the pedal is pressed.
Does this signal have to be enabled in software?
What is the signal voltage?
I'm no expert on this but I'll give it a shot. I tow and have the Prodogy P3 as well. When you say you use the override, are you talking about the manual brake lever on the P3? That would be the only way to get a voltage reading while stationary. The P3 doesn't send any current until it senses the vehicle braking so you'd have to be moving to read it. And I believe the voltage increases as braking increases which increases the braking at the trailer. What that range is I don't know.
Yes if I use the manual override lever on the P3 I get full braking on the trailer. So the braking circuit is hooked up to the trailer.
But I would expect the brake sense signal from the cayenne to signal braking with the brake pedal depressed, otherwise there is no need for that circuit and the relay. Perhaps the car has to be in motion for the signal to change. I may have to do a moving test.
Yes if I use the manual override lever on the P3 I get full braking on the trailer. So the braking circuit is hooked up to the trailer.
But I would expect the brake sense signal from the cayenne to signal braking with the brake pedal depressed, otherwise there is no need for that circuit and the relay. Perhaps the car has to be in motion for the signal to change. I may have to do a moving test.
The P3 applies brakes based on motion, not the brake pedal.
On the P3, enable "boost" and try it. that will send some voltage even when stationary and the brake is applied.
Otherwise, it doesn't sound like the P3 is getting a signal from the car that you're pressing the brake pedal.. You can check that in one of the menus.. ("brake light voltage" I think it is)
As long as the P3 controller sits level on a horizontal plane and is pointed in the direction of travel, it will sense - via an internal inertia sensor - how your tow vehicle brakes. This inertia-based sensor responds to the deceleration of your tow vehicle as you brake by signaling the controller to send out enough power to your trailer brakes so that they are activated with an intensity that matches. The result is uniform braking across your towing setup. No push-pull action - just smooth, proportional braking every time.
I just used the P3 for the first time this weekend. I believe it still showed some signal going to trailer when completely stopped but I could be wrong. Try going for a short drive and see if it puts out any voltage at all. Like the others said try the boost settings and see how it acts. Mine worked great, was originally using the the wireless curt echo and that thing suck for me. Not sure if it was an issue with the truck but it was horrible. Would recommend the P3 to anyone with a cayenne and intentions of heavy towing.
Just thought I'd note an interesting thing I found today... if your Cayenne alarm is armed, and you unplug your trailer 7-pin connector, the alarm goes off. Nice security feature.
For whatever reason I am not getting a braking signal from the Cayenne wiring. I suspect its something that is enabled in software.
To get the running lights to work I had to use a 5v/12v relay and picked up the signal from the tail light.
I think I am going to have to do the same for the brake lights and brake controller. Run a new wire from the tail lights to the controller at the front. I did a test with a simple 12v signal to the Tekonsha, and it seems to respond and modulate.
What a pain. You would think it would be easy to add a tow package, to any SUV. If I thought adding the Porsche Tow computer would do it, I would go that way, but its a very expensive gamble.
How is the controller mounted? I do remember reading that the P3 was pickier about how it was mounted vs the P2 (what I have). I run B2 for my boost (~5-5.5k lbs)
07-16-2020, 07:46 AM
Electric Trailer Brake Controld Signal Problem
