Forum Discussion

wgriswold's avatar
wgriswold
Explorer
Sep 26, 2016

Slack in 7-pin Cord

Since I got my new truck last February it has been complaining about low battery voltage and now also tells me to check trailer wiring. I have taken it to the Ram dealer and they found nothing wrong with the truck. So I think the truck is smart enough to monitor the trailer.

On my last trip I had Autozone check the trailer batteries and they said they were defective. I replaced them but the problem is still there. So I think the problem is with the wiring on the trailer.

I am going to replace the 7-pin cord and plug. Several years ago the cord dragged and I repaired it. The plug is original and the spring type where the male plug is squeezed between two metal connectors and the squeeze connectors seem to be weak. So replacing them is a good next step in solving this problem.

So the question is, once the cord is stretched tight to reach the socket on the truck, how much slack should be added to account for turns? I am hoping there is some rule of thumb so I get it right. I can't just duplicate the current cord since the truck has a different position for the socket and the cord is now too short. I have been using an extension cord but want to eliminate that.
  • cmeade's avatar
    cmeade
    Explorer
    Sep 26, 2016
    Probably not on topic, but due to open heart surgery I did not drive my 2010 Ram CTD for several months. I went to start it and starter solenoid clicked. Put 2 battery chargers on it and same click but wipers came on. After batteries charged it started but seemed weak and trailer connection warning displayed (trailer 500 ft away). It was also stuck in 4th gear (cruise on for fast idle). It is an automatic trans. Test drive and was in fact stuck in 4th gear! This was all from a low voltage condition. Disconnected Power distribution box pos lead and held brake pedal down 30 sec and tranny came back and power too but CEL now on. Remote start will start it but dies after 5 secs. Reset 7 problem codes and all is great again. My point is low voltage is nothing to play with on Rams and you need to have a second opinion or a third so you do not go thru what I did. My old 1989 Chevy 3500 I could jump start and drive away. The good old days!!!!
  • Strabo's avatar
    Strabo
    Explorer
    Sep 26, 2016
    Our 7 pin will pull out just enough when I make a tight turn, then I have no trailer brakes. So I zip tied the socket and 7 pin together. Then I made a very tight turn one day and broke off the cover on the socket receiver. I would like the socket for the 7 pin installed in the bed. $125 is the cheapest so far as an estimate. Newer trucks come this way now.
  • Vintage465's avatar
    Vintage465
    Nomad
    Sep 26, 2016
    rbpru wrote:
    My cord takes a loop around the tongue jack then makes a bellied droop to the plug. It has about 6 inches of slack but since it rides on the hitch it does not need much slack, if that makes sense.


    Normally I like the idea of the cord making a loop around tongue jack too.
  • deltabravo's avatar
    deltabravo
    Nomad
    Sep 26, 2016
    It's a pretty common problem with trailers having a plug that isn't made to the exact specifications in diameter, so the plug fits loose in the truck's OEM receptacle.

    I hear about a lot on GM truck forums. I experienced it myself too. I had never heard of the problem until I was describing my symptoms to the dealer I bought a cargo trailer from. He explained it and some some brands of trailer pigtail plugs fit loose in OEM receptacles.
    I changed the pigtail, problem solved. That was about 3 years ago, and I've never gotten the "check trailer wiring" on the DIC again.
  • mike-s's avatar
    mike-s
    Explorer
    Sep 26, 2016
    wgriswold wrote:
    how much slack should be added to account for turns?
    This is easy - if the cord can be easily stretched so it can go directly over the top of the hitch ball, it has enough slack. (If it were routed over the ball, it wouldn't need any slack)
  • rbpru's avatar
    rbpru
    Explorer II
    Sep 26, 2016
    My cord takes a loop around the tongue jack then makes a bellied droop to the plug. It has about 6 inches of slack but since it rides on the hitch it does not need much slack, if that makes sense.
  • samandtheduck's avatar
    samandtheduck
    Explorer
    Sep 26, 2016
    I use a short bungee cord to take the slack out of the cord which allows the cord to stretch a little when required.
    Brian

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