User 52121

I have no idea.

I can tell you that I did NOT install a relay and I have NO issues with my Tekonsha P2.

bweSteve

I installed my Tekonsha P3 without a relay, and have had zero problems for 2 years now.

I read all the threads (up to that point 2 yrs ago) too, and never really understood why I would need one either. But I'm no electrician.

docwyte

I installed a relay. Why wouldn't you? Its not like its expensive or complicated...

BlueJay73

I just want to know why do you need one.
Without one, is something not working correctly, like the trailer brake lights, or the trailer brakes?
I am very mechanically inclined, but not electrical circuit inclined at all. I don't know what to get, where to get it, or how to put it together.
I'm ashamed to admit it, being a hard core DIYer, but I need spoon feeding when it comes to wiring.

DarylJ

I've been going through the brake controller threads so this is second hand potentially correct information:

It appears that the system for detecting brake lights out sends a fluctuating 3-4v pulse when the brakes are OFF and the expected 12v when they are on. Some brake controllers freak out about this as they expect either 0v or 12v. Some brake controller don't care. If yours does, you need a relay.

quickster2

Thanks for all of the help on this forum. Tekonsha Primus iQ installed without a problem using the VW connector. Ready to tow the Viper to the track now and can take the Cayenne out for a couple of laps as well.

stronbl

I think people had issues with Cayenne's before the 958 model, so the relay fixed those (see post #20 above from DarylJ for info). So far I have not heard anyone with a 958 needing a relay, but many of us wired it "just in case" since it is a $.50 part from an auto parts store.

bweSteve

Is "relay" in this case, the same as a inline fuse? I'm still confused on what the relay is supposed to switch to/from.

And yes, I have a 2012 958 CTT.

But I also think I am hearing that you guys are saying the "relay" only really comes into play if your trailer lights go out or dead,... and that's when the relay switches.

DarylJ

A relay is an electronically controlled switch. In this case you would use the brake wire as the power to turn the "switch" on and off, as it won't go "on" with just 4v. Then the other side of the relay (the load terminals) would go from any 12v source to the brake line on the trailer brake controller.