Seven pin replacement socket wiring questions….2008 Knight - used primarily for Trailer towing

[Steve P]

The socket for my toad/trailer has survived for 15 years but needs replacing.  The owners manual (pic #1) seems different from the existing socket (pic #2) in that there is no red wire for starters.  And online has 2 variants (pic #3).  The back of the existing socket is filled with what appears to be silicone caulk, but I suppose one can guess what wire goes to what terminal around the perimeter by careful inspection of the socket.

Edited: The more I look at the photo of the existing socket, the more it looks like the 7-way traditional wiring, which is what I'd expect.  But that is quite unlike the owners manual.  Puzzling, eh?

Any other pointers or thoughts?   I really appreciate your help! 

[Tom Cherry]

Don’t rely on pictures.  Use a test light or a VOM and pin out each wire.  You need to make it like it is….assuming it is working with whatever you plug into it.  DVOM’s arE notoriously picky when trying to get a left and right turn, or at least mine it.  Use the DVOM and locate the five you know.  It you haven’t hooked up a brake controller, then the blue wire will have no signal.  You can also use a trick that many use.  Use a needle and then prick or put the needle in each wire.  Then use your VOM and do a continuity test and find which wire goes to which pin on the connector.  I’m willing to bet the the blue wire will be the 7:30 location, in the Trailer plug upper left photo, more correctly. It should be the 4:30 pin on the MH end….which is obviously a reverse or mirror image.  
 

So….use the needle and pierce each wire and find out where it in on the 7 pin connector and just put on a new connector.  If you opt for the one with the 4 pin, then verify.  The 4 wire is standard so, follow the color or position.

[Steve P]

@Tom Cherry Thanks!  The one step at a time approach that you described is what I needed.  I'm in that pre-travels crunch mode where haste can take over... never a good thing.  I do have a Brake Buddy, so the blue wire does work.  One of the reasons I'm replacing the socket is because a brake light control relay in the R. Rear run bay keeps popping, seemingly due to heat.  The connections in the current socket seem loose, partly due to age and cracks, and may be creating resistance, thus heat (purely a theory at this point).   I've been chasing that gremlin on another thread. 

One question:  you referred to the first diagram and said you'd bet the blue wire would be at 7:30, where the white wire is shown.  Why? 

[Tom Cherry]

10 minutes ago, Steve P said:

@Tom Cherry Thanks!  The one step at a time approach that you described is what I needed.  I'm in that pre-travels crunch mode where haste can take over... never a good thing.  I do have a Brake Buddy, so the blue wire does work.  One of the reasons I'm replacing the socket is because a brake light control relay in the R. Rear run bay keeps popping, seemingly due to heat.  The connections in the current socket seem loose, partly due to age and cracks, and may be creating resistance, thus heat (purely a theory at this point).   I've been chasing that gremlin on another thread. 

One question:  you referred to the first diagram and said you'd bet the blue wire would be at 7:30, where the white wire is shown.  Why? 

You are correct.  I was referring to the trailer or “what i plug in” photo.  On my iPad, that was the one that I could easily scroll up to.  But, as you pointed out, I should have used the diagram for 5he MH end, which is a mirror image so put my bet on BLUE 4:30…then see if I win.  Trust (diagram) but verify.  

Good Luck.

[Dr4Film]

Steven,

Just cut the old one off and start from scratch.

You will notice that the "traditional" and "RV" lug positions are the SAME as to their functions and specific position. Do NOT pay any attention to wire colors.

As Tom stated you will need to profile each wire you have now as to their function then wire the new one according to the RV diagram.

[lake49068]

Don't understand the reference to a "Brake Buddy" on the blue wire.  Thought that the BB got its power through the toad's 12v system not directly from the coach connection.  Except there is usually provision for keeping the toad's battery charged from the "hot" 12v line from the coach.

[Dr4Film]

7 minutes ago, lake49068 said:

Don't understand the reference to a "Brake Buddy" on the blue wire.  Thought that the BB got its power through the toad's 12v system not directly from the coach connection.  Except there is usually provision for keeping the toad's battery charged from the "hot" 12v line from the coach.

I agree! The Brake Buddy doesn't need a brake controller to work nor should there be any voltage on the blue wire unless a brake controller is sending voltage down through it.

Very strange indeed.

[Steve P]

It's not how the BB is powered.  The question is, where does the BB get the brake signal from?  It's either the blue wire, or a combination of the left turn/brake wire and the right turn/ brake wire.  I'll need to drag out the BB manual and read, but which it is, is not my foremost concern at the moment. 

[Dr4Film]

My guess is that you must have a different model of Brake Buddy than the classic model that is portable and has proportional braking.

[lake49068]

Inertia switch internal to the BB.  Does not rely on an external signal.

[Tom Cherry]

42 minutes ago, lake49068 said:

Inertia switch internal to the BB.  Does not rely on an external signal.

Assuming you have one without the wireless remote which is also a monitor as well as a controller that lets you adjust the “level/stage/intensity” of the braking.  The first version of these circa 2006 were more of “maybe I will work” and barely would communicate with a BB on a rig longer than the low 30’s.  BB used my 36 Winnie, finally, as a Beta tester and sent me two revisions to the control circuitry and at least one to the controller….  I had forgot about that….but eventually installed the US GEAR and eBayed the BB as BB said “Do NOT install in any towed vehicle with Electro/Hydraulic (non Vacuum powered Hydraulic) braking system….

FWIW….  BB insisted that I install a 20A inline fused power plug to proved adequate 12 VDC as well as “positively” make sure their power plug was in a suitable receptacle…..And suggested that the towed vehicle have a charging circuit or be run at least 30 minutes every 4 hours or so….  Yes, I was on the “development tech’s Christmas card list”…. LOL

[Steve P]

BB model 39504 with remote controller & monitor.  Dealing with duplicating wiring at the moment, so what controls the BB is not the hot topic.  🙂  I will get to that later... it works on existing trailer connections and should (and must) after replacing the socket correctly!   So that is where my efforts are focused and concentrated at the moment.

Current wiring looks like this looking at the blade side of the socket on the RV (what you see when you flip up the dust cover) :

By the way, I cut off the socket from the RV because I was getting 2 and 3 blades that would show connectivity to some of the wires. Then I pierced The wire ends with a safety pin and did continuity checks with my analog VOM and this is what I got below/attached.

 

[Tom Cherry]

17 minutes ago, Steve P said:

BB model 39504 with remote controller & monitor.  Dealing with duplicating wiring at the moment, so what controls the BB is not the hot topic.  🙂  I will get to that later... it works on existing trailer connections and should (and must) after replacing the socket correctly!   So that is where my efforts are focused and concentrated at the moment.

Current wiring looks like this looking at the blade side of the socket on the RV (what you see when you flip up the dust cover) :

By the way, I cut off the socket from the RV because I was getting 2 and 3 blades that would show connectivity to some of the wires. Then I pierced The wire ends with a safety pin and did continuity checks with my analog VOM and this is what I got below/attached.

 

OK...did NOT know that Brake Buddy was using hardwiring....so here is my comment.... Your Diagram...

Black - That SHOULD be the Charging circuit.  It ONLY works with the KEY ON. There is a relay in the back (20 amp circuit breaker) that is energized from an IGNITION on Circuit.

Green- The Universal GREEN - RIGHT Turn/Flashing...and ON when you apply the service brake...

Blue - the INFAMOUS "signal" or 12 VDC coming from a "owner" installed Brake controller...can be for a TOAD (like the old US Gear) or a utility trailer controller.  There will be NO SIGNAL (as the front wire is unterminated in a connector) if that circuit has not been installed...or NO SIGNAL.

White - GROUND

Yellow - Same as the GREEN (that is WHY they are opposite) except for LEFT

Brown or sometimes TAN... Tail or clearance or running lights.

Center...GOD ONLY KNOWS...supposed to be Backup.  

NOW meaningless trivial.  IF one has a 6 PIN Umbilical and does NOT what to CUT and REWIRE...but needs the BLUE circuit... Hopkins makes a 7 to 6 adapter.  The Center (Purple) and the 4:30 Blue are interchangeable.  You remove the cover and reverse them if some well meaning person decided the BRAKE Signal was supposed to, erronously, be in the CENTER.  I had an Umbilical wired for a US Gear so I then proceeded to use the 7 to 6 and then configured the 4:30 so it was the BRAKE.  Worked for many years.  I finally, after trading off the old Hummer, rewired my Umbilical to a 7 Pin...so I got a few wires left over.  

You look good to go...if that was what your intent was....

[Guest Ray Davis]

There is no hard rule that the 7 pin connector must be wired properly as long as the toad & coach match. However, there is a proper or recognized arrangement of wires that should be used.  That way you can pull anything.  Color codes are roughly standardized but can't always be trusted.  You never know what may have been changed by someone.  I'm trying to remember, but I don't think your wiring matches mine.    Some 7 pin plugs don't come with wiring instructions,  I bought a Curt at Camping World with no instructions, but the one from Walmart had wiring instructions.   Here is a diagram from google.

 

 

 

 

 

 

 

 

 

Edited August 23, 2023 by Ray Davis

[Steve P]

On 8/23/2023 at 12:54 PM, Ray Davis said:

There is no hard rule that the 7 pin connector must be wired properly as long as the toad & coach match. However, there is a proper or recognized arrangement of wires that should be used.  That way you can pull anything.  Color codes are roughly standardized but can't always be trusted.  You never know what may have been changed by someone.  I'm trying to remember, but I don't think your wiring matches mine.    Some 7 pin plugs don't come with wiring instructions,  I bought a Curt at Camping World with no instructions, but the one from Walmart had wiring instructions.   Here is a diagram from google.

 

 

 

 

 

 

 

 

 

Yellow is cut off... and the rest of the blades are defined in yet another variation.  Previous posts were correct.  One needs a VOM to test each wire.  Or if replacing a plug or socket that was working before it broke, wire exactly the same.  If that fails, bang head and get out the VOM.

[Tom Cherry]

On 8/23/2023 at 12:54 PM, Ray Davis said:

There is no hard rule that the 7 pin connector must be wired properly as long as the toad & coach match. However, there is a proper or recognized arrangement of wires that should be used.  That way you can pull anything.  Color codes are roughly standardized but can't always be trusted.  You never know what may have been changed by someone.  I'm trying to remember, but I don't think your wiring matches mine.    Some 7 pin plugs don't come with wiring instructions,  I bought a Curt at Camping World with no instructions, but the one from Walmart had wiring instructions.   Here is a diagram from google.

Steven is correct….one can modify the 7 pins any way they want.  However “good standard practice” is to use the SAE accepted or Industry standard.  The prin above is a repeat of at least 2 other illustrations and also the “note book” schematic.  As is, the wiring is correct…install it like it was.  The Hopkins 7 pin to 6 pin adapter commonly used, as I did delete the # 7 Back Up lights circuit.  Pins 1, 5, 3, 4, & 6 are “fixed” or hard molded in.  They match the older MH/RV 6 pin SAE prints.  The option is for whether you need backup lights or a brake circuit.  This the last or sixth pin on the adapter can be either pin 2 for brakes or pin 7 for backup.  If you look at the instructions for most MH Umbilical kits, you see that SAE diagram for installation on your toad.

Following the industry/SAE standards ensures you don’t have to rewire a trailer or a toad.  All licensed (commercial built) trailers that come with a 6 or 7 pin plug will be to the SAE code….unless some ‘I’m smarter than them” individual has added a 6 or 7 pin to their towing vehicle with no knowledge or ignored the industry standard….  Most of the time, when purchasing or borrowing or renting a utility trailer or car hauler or whatever….the plugs meet the “code”…

Why change a SAE standard?  But folks do weird and non conventional and “destructive” wiring modifications all the time….and a lot of the “OMG…why don’t it work” posts are finally resolved…most of the time…undo and rewire properly….

We old time design/manufacturing/tooling engineers usually had a big red rubber stamp. MILTP or Make It Like The Print….  If that was super critical…one might have a second.  MILTFP.  There are times that members who contribute or assist others with wiring issues have mused, offline of course, that we needed a MILTP emoji….but we are nice….so professionally write a narrative to that effect…  😂 

 

 

 

 

 

 

 

 

 

[ziaptrn]

I was cleaning up some files and ran across this photo that I took that shows the Monaco wiring for the 7-pin tow plug on our 2008 Dynasty Diamond IV. The benefit to me was the inclusion of the Monaco wire colors, so that I could be sure of the proper wire for the new/replacement plug matching the OEM wires.

I thought this might be useful for someone (?) or just to save for anyone interested.

John

Edited September 10, 2023 by ziaptrn
clarify