Originally Posted by Burloak
... mmm well the automotive 7 wire connector and cable does support back up lights.. For whatever reason the rv industry chooses not to implement them on trailers.
The RV-style 7-pin connector (which is not the same as the SAE-defined 7-pin connector used for trucks) does have an auxiliary
pin (the one in the centre), which has no standard assignment - "auxiliary" means use it for whatever else you need that isn't in the standard. It certainly can
be used for backup lights, but it can also be used for a separate stop lamp circuit, or anything else the user wants. The tow vehicle side can't count on the trailer connecting this to backup lights, and the trailer side can't count on the tow vehicle supplying this from the backup light circuit.
What I meant by "RV trailer electrical connections do not include the backup light circuit" is that the tow vehicle doesn't necessarily have the backup light circuit hooked up, even though there is a pin that can be used. Maybe it often is hooked up to backup lights; there's just no assurance.
I know that some published diagrams show the centre pin on the RV 7-pin connector explicitly as backp lights, but that is incorrect. Similarly, pin 7 (the bottom pin) of the SAE J560 standard 7-pin used by commercial trucks is sometimes shown as backup lights, but is actually the auxiliary pin of that connector and now used for anti-lock brake system control.
I don't blame Escape and other RV trailer manufacturers for not putting on lights that may not work, may cause problems with some tow vehicle wiring, and are not even wanted by many buyers. The lights may not be a big expense, but all those little expenses add up. In my Boler the manufacturer provided a wire from the auxiliary pin of the connector the back of the trailer, not connected to anything, so the user could hook it up for what they needed, without fishing wire through the trailer - maybe Escape could do that.
If RV trailer owners want to use the auxiliary pin to run backup lights, I say go for it... but don't count on the trailer being compatible with anyone else's tow vehicle (I would put in a disconnect switch on that circuit), and don't count on the tow vehicle being compatible with any other trailer (again, a disconnect would be wise).
Another option is to install the desired lights, wire them to the trailer battery, and control them with a manual switch. When you get out to look where you are going to back up, you can flip the lights on. I haven't done this yet to a trailer, but it's in the projects-to-do list. I think docking lights (mounted near the front of the trailer and facing back along the side) would be more useful to the driver than a backup light on the rear, but I agree that one on the rear sends a clear "watch out, I'm backing up" message.