7 pin wire harness problem

jetmechoh · 04-30-2019, 05:08 PM

I have a wiring problem that is giving me fits. When we picked up our 2019 Salem Hemisphere there was a problem with the left turn signal not working. The dealer played with it and came to the conclusion that the problem was with my truck. They jiggled to connector around and finally got it to work. Needless to say this did not last long. I tried to eliminate the possibility that it was my truck wiring by first putting one of those testers that look like the plug. Everything worked with the tester. I had my son hook up to the trailer with his new 2019 truck and still no left turn signal lite. I took it back to the dealer and insisted that they change out the trailer cord under warranty. Picked up trailer and everything worked fine. First trip we took, I have the same problem except now it is the right side turn signal and brake lite that does not work. Is it possible that I could have gotten another bad cord? Dealer does not want to fool with it as he is convinced it is my truck. Any ideals on what to check? Thanks in advance for your help.

TitanMike · 04-30-2019, 05:25 PM

Your problem could be where the cord joins the wiring in your trailer. Usually this occurs in a plain old residential junction box located at the end of the cord with all the trailer wires running into it from two other directions. Open the lid and check connections at the end of the cord's wire. The Left and Right turn signal wires are Red and Brown (usually) and there could be a bad connection at that point. Mine were just crimped on butt connectors. To make sure the connections are good just hold each wire going into the connector and give it a tug. If good it won't come apart. If it does, you have your answer.

The fact the problem changed sides when they replaced the trailer 7-wire cord would make these connections very suspect.

If you want to see if power is passing through a connection even though it can't be pulled apart, put a sewing needle into the wire, through the insulation, and check for voltage on the side that connects directly to the light using your multi-meter touching the needle.

rockfordroo · 04-30-2019, 05:28 PM

The 7-pin umbilical cord should run into a junction box attached to the frame near the front.

First think I would do is pull the cover on the J-box and check the connections. They wire them together with wire nuts, but they don't always do a very good job.

I'm attaching what the wiring color code is SUPPOSED to be, but I know my Mini Lite did NOT follow the color code once the wires reached the J-box.

jetmechoh · 04-30-2019, 06:23 PM

I opened up the junction block and checked with a test light. All the different connectors worked with the exception of the brown wires. Got nothing there. I had the wife jiggle the plug at the truck and I briefly had them working. The connector that came from the factory and the new connector do not fit real tight. Seem to have a lot of play. That would lead me back to my connector on the truck being bad. (It is one year old, replaced it before picking up camper). The thing that makes me think it is ok is the fact that the lights don't work when my son hooks up his new truck to it.

EdJunior · 04-30-2019, 08:43 PM

What kind of truck?

jetmechoh · 04-30-2019, 10:09 PM

2005 GMC Sierra 2500 HD

**Bama Rambler** · 05-01-2019, 11:23 AM

It could still be the umbilical cord connector. Is it a molded on connector? The dealer could have just swapped it with a cord from another RV on the lot, if they replaced it at all.

I'd get a after market plug and cut the factory plug off and replace it. that will eliminate the cord connection from the mix.

TheWolfPaq82 · 05-01-2019, 11:38 AM

Quote:

Originally Posted by jetmechoh

2005 GMC Sierra 2500 HD

Your truck or your sons truck ??

jd50i · 05-01-2019, 11:47 AM

First thing I would do is look at the trailer plug and see if any of the contacts were damaged or distorted. I would try slightly squeezing them for a tight fit. I would also either connect to TV and wiggle it around and see if lights cut on and off or use a ohm meter on the trailer plug moving it around to see if there are bad connections inside.

TheWolfPaq82 · 05-01-2019, 12:12 PM

Quote:

Originally Posted by jetmechoh

2005 GMC Sierra 2500 HD

Reason I asked about who's truck was the 2005 is if your truck is a 2005, the first place I'd go is the connector on your truck. Those connectors are not "Water Tight" at least I've never seen one...and being it's 13 years old...I'd first suspect corrosion in that connector and I check every wire going into the back of it. When I lost my trailer brakes on my on my old Jayco, I spent hours going thru the brake system on the trailer, the cord on the trailer and the LAST place I looked was the truck connector. BINGO !!! the brake wire had corroded inside the connector and had to be cut off, restriped and reinstalled.

rockfordroo · 05-01-2019, 02:14 PM

Quote:

Originally Posted by TheWolfPaq82

Reason I asked about who's truck was the 2005 is if your truck is a 2005, the first place I'd go is the connector on your truck. Those connectors are not "Water Tight" at least I've never seen one...and being it's 13 years old...I'd first suspect corrosion in that connector and I check every wire going into the back of it. When I lost my trailer brakes on my on my old Jayco, I spent hours going thru the brake system on the trailer, the cord on the trailer and the LAST place I looked was the truck connector. BINGO !!! the brake wire had corroded inside the connector and had to be cut off, restriped and reinstalled.

X2. When I bought my 2009 Silverado in 2012, the 7-pin didn't work. I happened to have a new one in my garage (long story). Replaced it and all was good.

If you have the 7-pin only receptacle, the GM version runs about $45-50, but Hopkins makes one for about $10-15.

GM PN 12191503
https://www.amazon.com/Genuine-Parts...WAW6Y5YP0Q0711

Hopkins PN HM40930
https://www.etrailer.com/Wiring/Hopkins/HM40930.html

jetmechoh · 05-01-2019, 02:39 PM

My truck is the 2005. Because it was old I installed a new connector on it last April before I picked up the camper. I also mounted a new Class 4 hitch because of rust on the old one. The cable on the camper is moulded. I tried tightening the connector pins and was able to get a connection briefly. Forest river has the wiring going into a house style junction box that is full of holes. I am going to order me a new cable with the plastic water tight box. If that don't work then I guess I will change out the receptacle on my truck.

jetmechoh · 05-01-2019, 02:46 PM

This is the receptacle I installed last year.

It is made by Hopkins.

EdJunior · 05-01-2019, 06:25 PM

I asked what kind because on my new F-250, the plug does not sit in the receptor properly. Very loose. I have to zip tie it to keep it in. It connects okay, but just is not a tight fit at all. I plan on replacing my cord on the trailer.

Larry-NC · 05-01-2019, 07:52 PM

Quote:

Originally Posted by EdJunior

I asked what kind because on my new F-250, the plug does not sit in the receptor properly. Very loose. I have to zip tie it to keep it in. It connects okay, but just is not a tight fit at all. I plan on replacing my cord on the trailer.

The spring-loaded lid on the truck receptacle is supposed to latch over a ridge on the trailer plug, in order to retain it.

Maybe if you look carefully at it, you can figure out why it's not working on your truck.

Larry

TheWolfPaq82 · 05-02-2019, 07:14 AM

Quote:

Originally Posted by jetmechoh

My truck is the 2005. Because it was old I installed a new connector on it last April before I picked up the camper. I also mounted a new Class 4 hitch because of rust on the old one. The cable on the camper is moulded. I tried tightening the connector pins and was able to get a connection briefly. Forest river has the wiring going into a house style junction box that is full of holes. I am going to order me a new cable with the plastic water tight box. If that don't work then I guess I will change out the receptacle on my truck.

I'd check it again. If you live in an area like me, winter can be harsh on those connectors.

retiredcamper47 · 05-02-2019, 03:32 PM

Try spraying PB Blaster on the trailer plug and the plug in on your truck. PB Blaster does many things and is also an excellent contact cleaner. Just saying.............

Bob

EdJunior · 05-02-2019, 09:09 PM

Quote:

Originally Posted by Larry-NC

The spring-loaded lid on the truck receptacle is supposed to latch over a ridge on the trailer plug, in order to retain it.

Maybe if you look carefully at it, you can figure out why it's not working on your truck.

Larry

Thanks Larry. I did, and it sure doesn't "fit" quite right. But the whole plug is just loose. When I lift the latch, the plug just falls out. It's pretty crazy. On my 2011, it was really tight...no chance of falling out. I've read where a couple of other new F-250's had this issue, but it doesn't appear to be a rampant problem. Very strange.

Larry-NC · 05-02-2019, 10:18 PM

Quote:

Originally Posted by EdJunior

Thanks Larry. I did, and it sure doesn't "fit" quite right. But the whole plug is just loose. When I lift the latch, the plug just falls out. It's pretty crazy. On my 2011, it was really tight...no chance of falling out. I've read where a couple of other new F-250's had this issue, but it doesn't appear to be a rampant problem. Very strange.

Something's off spec, either the plug or the receptacle. Experiment with different brand plugs and different brand receptacles until you figure out which one. Then change the off-spec part.

Larry

rockfordroo · 05-03-2019, 09:14 AM

Quote:

Originally Posted by EdJunior

Thanks Larry. I did, and it sure doesn't "fit" quite right. But the whole plug is just loose. When I lift the latch, the plug just falls out. It's pretty crazy. On my 2011, it was really tight...no chance of falling out. I've read where a couple of other new F-250's had this issue, but it doesn't appear to be a rampant problem. Very strange.

A turn or two of electrical tape around the plug will hold it in, but may or may not help with actual pin contact.

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