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Author Topic: Problem hooking up 4 flat to 7 blade wiring kit  (Read 555 times)

cmd1965

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Problem hooking up 4 flat to 7 blade wiring kit
« on: May 28, 2019, 10:35:32 PM »
Good evening all!
Sorry in advance if this is drawn out, but I'm not sure what I'm doing, so I'll ask.
DH and I are trying to hook up the towing lights for our new to us 2003 X-Treme Lite hybrid TT. It has the 7 blade connection. We have 2 tow vehicles: 2001 Dodge Ram conversion van and a 1991 Ford F150 pick up. Both have the 4 flat connection. We didn't have the correct connector when we purchased the camper from a private seller, so we chanced it coming home (me driving our car right behind him the whole way, lol).
I've purchased the correct connection, a Hopkins connector, # 47205. I thought all I had to do was plug them together and ground and it should work. But it didn't. So, what am I doing wrong? And, how do I test if the problem is on the TT side?
I've tried looking up some troubleshooting, but all I get are usually about motor homes and tow vehicles.
I yield to the experts and thank them in advance for your help.
 ???

Lowell

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #1 on: May 28, 2019, 11:24:53 PM »
Does you TT have electric brakes?  If so, you will need a brake controller in the tow vehicles wired to a 7 blade connector to mate with the TT connector.
Lowell
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John From Detroit

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #2 on: May 29, 2019, 06:54:27 AM »
The flat 4 is Right Stop/turn. Left stop/turn. Tail/marker/license plate and Ground.

the 7 pin adds battery charge. Electric brake and "AUX" (sometimes used for back up lights or other uses)

If the trailer has brakes and I'm guessing it does.  You need to upgrade tow vehicle to control them.
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Rene T

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #4 on: May 29, 2019, 07:29:37 AM »
https://www.etrailer.com/Wiring/Tow-Ready/118709.html?feed=npn&gclid=EAIaIQobChMI6KGD_dzA4gIVV7nACh1GIQceEAQYASABEgJE4PD_BwE

This is for going from a 7 pin on a tow vehicle to a flat 4 pin on something like a small utility trailer. Not what they need.
They have a flat 4 pin on the tow vehicle and want to connect to a 7 pin on the RV. Unless I read it wrong what they were saying.
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Gary RV_Wizard

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #5 on: May 29, 2019, 09:57:03 AM »
Agree with the others - there is no adapter that will magically make up for the 3 pins that are lacking one 4-pin connector on their tow vehicles.  The 4-pin can make the trailer stop/turn/tail lights work, but not the trailer brakes.  The tow vehicle(s) need an electric trailer brake controller installed and wired to a suitable 7-pin connector at the back.
« Last Edit: May 29, 2019, 09:59:34 AM by Gary RV_Wizard »
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Matt_C

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #6 on: May 29, 2019, 10:32:11 AM »
Listen to Gary....

You can leave the 4 pine there if you chose, but make both possible tow vehicles 7 blade RV connectors.  This will end a world of problems you have not faced yet. 
As Gary also said, that trailer probably has electric brakes.  If it does not, the next one will. 

Matt 
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Lowell

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #7 on: May 29, 2019, 11:02:49 AM »
The OP might consider going to U-haul to get a Brake Controller and 7-pin receptical installed.
« Last Edit: May 29, 2019, 12:23:26 PM by Lowell »
Lowell
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phil-t

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #8 on: May 29, 2019, 12:20:38 PM »
Read here. - If all you need is lights on the trailer get their adapter.

I would get the 7-pin connectors for your two vehicles and get them wired in.  Doing this will/should insure no issues with the tow vehicles connection(s).

Good luck
« Last Edit: May 29, 2019, 12:24:15 PM by phil-t »
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grashley

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #9 on: May 29, 2019, 06:53:00 PM »
Welcome to the Forum.

As others have said, there is no simple plug and play to make 4 wires carry 5 or 6 signals.  This site will show normal wiring for different trailer plugs.

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

You do need to add a trailer brake controller to your tow vehicle of choice.
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Lou Schneider

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #10 on: May 29, 2019, 07:22:07 PM »
The Hopkins #47205 adapter referenced in the original question appears to be the correct to adapt from the signals in a 4 pin flat connector to a 7 pin RV socket.  The 3 lines not available on the 4 pin connector are brought out separately according to this illustration:

Keystone #47205 Adapter

So the question is whether the various light voltages are appearing on the correct pins on the adapter, or if the problem is in the trailer.

I'd start by using a circuit tester to verify the voltages are appearing on the correct pins in the truck socket when each light is activated.

Harbor Freight has an inexpensive circuit tester, connect the clip to ground and the handle will light up when the tip is placed on voltage.  You can probably find something similar in an auto parts store if Harbor Freight isn't nearby:

https://www.harborfreight.com/612v-circuit-tester-with-5-ft-lead-63603.html

Here's a diagram showing the pinouts for the 7 pin connector and socket:

7 Pin Trailer Connector and Socket

Don't forget to connect the brake controller, battery charging wire and ground wire that are brought out seperate from the 4 pin plug.

Once the truck socket checks out OK, then it's time to start looking at the trailer.
« Last Edit: May 29, 2019, 07:27:16 PM by Lou Schneider »

Gary RV_Wizard

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Re: Problem hooking up 4 flat to 7 blade wiring kit
« Reply #11 on: May 29, 2019, 08:16:22 PM »
Good catch, Lou. That #47205 does indeed have 3 extra leads to add the missing functions.  Question is, did cmd1965 install brake controllers in both the two vehicles and hook up the extra wire(s)?  Doesn't sound read like it.


Note that only one of the extra wires is for braking; another is for a constant 12v (battery charge), and the 3rd is an auxiliary that can serve a variety of purposes (none of them strictly needed).
Gary
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