Hi, I feel awkward asking this question as I am usually one of guys answering the wiring questions. So here goes. I recently (last week) bought a 2006 Paiute 18' flat bed trailer that needed all new lights & wiring. (it was totally stripped) I bought all new LED lights and here is my question? Because the trailer is wider than 80" it also requires a rear center clearance marker. The new rear center clearance marker has 3 wires (ground, tail & stop). So my question is how do I get the stop lite to work. I can't hook it to the trailer turn signal/stop light as it will flash when that turn signal is on. Also, if I hook it to the trailer brake wire (blue) it will only have partial voltage depending on the brake controller setting. Any help is greatly appreciated.

 

my 18ft car hauler has the center marker..thats it...no need for the brake wire...not sure why they have it....also being that wide don't you need corner markers?

U.S. reg's...
http://www.fmcsa.dot.gov/rules-regul...spx?reg=393.11

 

Best bet would be to tap into the brake light switch at the brake pedal, you will have to run a separate wire but will solve your need. Just tap the wire that's hot when brake is depressed.

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Four wires coming from the plug on the front of the trailer include:

Left turn signal
Right turn signal
Tail,running lights
ground.

That it. There is no "stop" light or brake light wire. Instead, when you want brake lights, you use both the left and right turn signal wires at the same time, without going through the flasher.

 

Steve, I bought the 3" corner markers as well as 6" oval combination stop/tail lights. I considered only wiring the tail light wire on the center marker but would prefer to have the stop portion function. Thanks for your help

 

agreed, does that wire run to the rear? I should have said earlier the two tow vehicles are 1) 2007 F150 with factory tow package and both 4 pin & 7 pin connectors and 2) 2008 F350 with factory tow package and both 4 pin & 7 pin connectors

 

Smokey, I plan on wiring trailer with a 7 pin RV type connector as the trailer has electric brakes on 1 axle. The trailer is rated at 7000 lbs GVW. Also if I wire both the left & right turn signal wires at the same time how do I keep the turn signal lights separated since the turn signal/stop light is the same wire on both 4 pin & 7 pin connectors. IE green=right/yellow=left?

 

All the trailers that I have seen with a center marker only use the tail marker function of the light. I think you could use something like this to get the center light working like you want without running a separate wire from the truck: http://www.etrailer.com/Tow-Bar-Wiri...92-118158.html

With the diode kit, you could leave it on the trailer and still only use the 7-way plug.

I don't think ford runs a brake only wire to the rear of their trucks. If you choose to just run a wire from the truck, you would need to tap into the brake switch or center high mount light and run that wire to the rear of the truck.

 

Watt-I got to thinking about it after I went to bed last night and thought about using diodes before I read your response. I'm going to measure the current draw of the stop light function of the marker and double the amperage of the blocking diodes. (IE if it pulls .5a use 1a diodes) It should function as follows:
connect both left & right stop light/turn signal together at the marker. Insert blocking diodes in both leads so the right doesn't affect left and vice versa. If successful, the following should occur:
1) under normal braking (no turn signals) left stop, right stop & center marker would light
2) Left turn with or without braking left turn and center marker would flash
3) Right turn with or without braking right turn and center marker would flash

This would be cheaper than the kit that you mentioned, use less parts and maintain trailer wiring integrity enabling it to connector to any standard 7 pin RV connector. I don't want to modify the 7 pin connector under any circumstances. As a last resort, if this doesn't work, just use the center marker as a tail lite as you mentioned.

I figured that you would respond as you seem to be the wiring guru. As always, thanks for your help and look forward to seeing you at SEMA 2014. BTW, when we head back to VA I'll be pulling the trailer with wife's blown 97' Mustang GT drop top (convertible) with less than 20k miles.(granny's grocery getter)

How far are you from ALB? We usually overnite there. I'll PM 'ya a couple of weeks before we leave.

 

Sorry, but automotive electric is beyond my pay grade. I wired my entire 3,000-sq-ft house, but 120-volt stuff is a lot different that automotive wiring. For my house, I didn't use even one relay or diode or fuse, just circuit breakers

http://www.etrailer.com/faq-wiring.aspx

Here are the 6 "hot" wires in a 7-pin RV plug. The missing wire in the white ground wire:

Right turn = green
Left turn = yellow
Tail/marker = brown
Brake controller (not brake light) = blue
12-volt hot - normally used for trailer battery charging = red or black
12-volt auxiliary hot - normally used for trailer backup lights = purple

Notice there is no brake light wire. So whether 4-pin or 7-pin trailer harness, there is no wire for brake lights. So the brake lights are activated by somehow using both the left and right turn signal wires. If I wanted to see exactly how they do it, I would study the wiring diagram for any trailer that has lights.