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I have a 2010 F150 with a prodigy P2 controller installed and the trailer is a 2015 PJ 16' car hauler with dexter axles ( 1 w/ brakes 1 w/o brakes) When I pull the trailer unloaded the controller will start to activate the brakes the display OL then display SH.
Now I know the OL is an overload, and the SH is a short.
The thing that is confusing me is once I have a car on the trailer it no longer has any codes. The brakes work good.
I know I need to check the brake magnets and the current pull of the brakes. It just has me confused that it only does it when the trailer is unloaded.
I am guessing you mean the latter, in which case, I would start by checking the wiring that runs to the brakes. It sound to me like you may have a frayed wire making contact with a suspension component. I would look for that first, before tearing down the brakes.
I think a bad or broken ground would open the circuit and give a "no trailer" message rather than a "short"/"overload" message.
You are correct... but I have seen back-feeds do ODD things..
and many trailers do have poor or bad grounds...and rely on a physical ground between receiver ball and socket... that should be greased.
I am not an expert in trailers.. but have lots of time fixing wiring in cars/trucks.
as he will be working on the wiring.. check everything...
but if the cord breaks its ground wire... bad connection...
I know the 10 plus white wires in my coachmen goes to the Frame...
if the thin ground wire going to the truck looses connection for any reason.. only ground between truck and trailer is the ball..
7 wire connector.. only 1 is for ground !?
am I right or WRONG??????
and the Main reason newer cars and trucks do NOT use the body/frame for a ground.. only tying body ground to electrical ground.. (negative path)
You are right In theory. What I question is how often it is an issue. I have found a broken ground in the seven pin cord to be rare. And I don't see how it is related to the OP's post. He has a short.
I have limited experience with 7 pin.. but tons of with 4 pin.
small boat and utility types.
and 80 percent of the time... trouble reports ends up being a ground issue...
He is having a problem.. while he is inspecting.. inspect brake wires AND ground wires.. may not help Now.. but Could show a possible problem soon.
and costs Him nothing but a little bit of time.
It rained all day here to day so i could not get out to look at the wiring. I had to replace the 7 pin plug last year but no problem after replacing it, so when the problem started I did take it apart and recheck all of the connections, but still have the error codes.
Thanks for the replys
There is usually stranded wire in the pigtail. I put one together for a TT and had one errant strand cause some occasional strange light happenings- but that was way before 'smart' controllers. In my case, it all seemed to depend on how I attached it to the female end or how it dangled between the vehicles.