TOAD wiring delemna........ugh!

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mikeylikesit

mikeylikesit

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Sep 15, 2017
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Location
Oakboro NC
The short question, is what should I be getting on a 4 pin round trailer connection coming out of the motorhome?

my understanding is..... ground, tail lights, left blinker/brake, and right blinker/brake. The lights on the coach work fine.


Well, I've wired up my Jeep with the Roadmaster diodes, exactly as indicated in the instructions, and I don't work.

What is weird is that I towed a borrowed flatbed trailer with the motorhome and the trailer lights worked perfectly..........however, when using a test light on the motorhome connector, I find..........

left and right brake/turn signal to the ground pin work fine.  When I turn the tail lights on, then it seems to have voltage on all 3 pins to ground. I'm hoping that I'm missing something simple.....

any ideas?

thanks folks! 
 
This is with nothing (like the Jeep) connected to that 4 pin connector?  I'd take the connector apart for a look.  If it's with the Jeep connected, check those diodes are properly installed for the purpose you want.
 
YOu are missin a ground.

}If you are talking about using a test light/meter on teh RV without a towed then it's the tail lights (most likely) on the RV but it might be the FRONT turn signals.. Mine was

IF it shows the problem WITH the jeep connected then it's the JEEPs ground

WHat is happening

When you turn on the tail lights voltage is appplied to the tail light element in the dual element lamps. then since it has no where to go it feeds back through the turn/stop elements so you see voltage on all 3 pins.

I have had it happen twice. Once it was the FRONT turn signal. I simply removed the lamp and re-seated it (The lamp was not making proper contact) the other time it was teh Towed.  I had to improve grounding.
 
you folks are awesome! Thank you.

Yes, this is on the MH with nothing connected. 

John, if I'm missing the ground, then how do the MH lights work at all?  (I guess what I mean is:  Is there a difference between "missing" a ground; and a "poor" or high resistance ground".  I like to learn. :)

anyway, I'll start at the tail lights. 

 
 
The ground is fine at the motorhome's tail lights, but it's gone missing at the connector.  Test the resistance from the connector's ground pin to a point on the motorhome's frame - I'll bet you'll find it's open.  Or probe the voltages on the connector with the ground lead of the test light connected to the motorhome frame instead of the ground pin in the socket - I'll bet they look normal.

When you towed the utility trailer, the missing ground to the trailer was replaced by the frame to frame connection through the hitch ball and the trailer coupler.  The tongue weight of the trailer broke through the grease residue to provide a connection.

A towbar doesn't have any weight on it so it's less likely to break through the crud.
 
EUREKA!

you guys were absolutely correct.  I started at the 4 pin connector on the rear of the coach, and sure enough, the wire and connection at the ground pin were green with corrosion.

So, I went into "marine wiring mode" and cut back each conductor to clean (bright shiney copper) wire, tinned it with solder, cleaned out the sockets for the wires to clean brass, added a little dielectric grease and buttoned it up.  Should not have to mess with that connector again.

Now, the MH tests correctly.  Still have an issue with the Jeep, altho I made some progress with the help of the EXCELLENT technical support folks up at RoadMaster.
I had installed the 6 diodes set up, but they told me I only needed 4 diodes.  So, that will be the project for this afternoon......

Thanks again for the timely responses!
 
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