Trailer Backup Light Harness Question

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Ramtop

Member
Joined
Jul 23, 2014
Posts
47
Reaction score
27
Ram Year
2019 Ram 2500
Engine
6.4L
I purchased a Magnum Truck Rack with built in brake/turn lights and back up lights. They provide a wire harness that you remove the feed plug from the trailer plug and plug their harness in which has a Y for the original plug to plug into. I have my brake/ turn lights but no back up. I am assuming it uses the trailer backup light function. I found a fuse for trailer back up lights and it is good. Anything else someone knows that I can check out?
 

John Jensen

Senior Member
Joined
Mar 27, 2016
Posts
1,511
Reaction score
1,646
Location
San Diego County
Ram Year
2016
Engine
Ecodiesel
I don't know the answer but suspect it's in the wiring. The truck reverse wire is white with a red stripe. Here is a trailer plug diagram that might help chasing the wiring.
 

Attachments

  • Trailer Plug Wiring.jpg
    Trailer Plug Wiring.jpg
    76.7 KB · Views: 24

Dinky

Senior Member
Supporting Member
Joined
Feb 2, 2019
Posts
2,196
Reaction score
2,464
Location
Oregon
Ram Year
2022
Engine
6.7
I purchased a Magnum Truck Rack with built in brake/turn lights and back up lights. They provide a wire harness that you remove the feed plug from the trailer plug and plug their harness in which has a Y for the original plug to plug into. I have my brake/ turn lights but no back up. I am assuming it uses the trailer backup light function. I found a fuse for trailer back up lights and it is good. Anything else someone knows that I can check out?

If all else fails have a buddy sit in the truck and use a test light on the rear plug. you will know what wire it is 100%then.
 

Socalramfan

Senior Member
Supporting Member
TOTM Winner
Joined
Feb 12, 2017
Posts
4,271
Reaction score
5,104
Location
Huntington Beach
Ram Year
2011 Big Horn
Engine
4.7
Is this what you have?


7C55746F-0DAA-4859-99E6-54ED0276A2C6.jpeg
 
Last edited:

Socalramfan

Senior Member
Supporting Member
TOTM Winner
Joined
Feb 12, 2017
Posts
4,271
Reaction score
5,104
Location
Huntington Beach
Ram Year
2011 Big Horn
Engine
4.7
Crap….
My whole response got erased……

retype it later.
 
OP
OP
R

Ramtop

Member
Joined
Jul 23, 2014
Posts
47
Reaction score
27
Ram Year
2019 Ram 2500
Engine
6.4L
If all else fails have a buddy sit in the truck and use a test light on the rear plug. you will know what wire it is 100%then.
Did that and have no power coming to the rear so I was hoping someone knew where else to look for the problem. The fuses that is marked for the trailer back up lights is fine. I don’t know if there is another fuse that also is used but not marked as such.
 

Dinky

Senior Member
Supporting Member
Joined
Feb 2, 2019
Posts
2,196
Reaction score
2,464
Location
Oregon
Ram Year
2022
Engine
6.7
Did that and have no power coming to the rear so I was hoping someone knew where else to look for the problem. The fuses that is marked for the trailer back up lights is fine. I don’t know if there is another fuse that also is used but not marked as such.

Check all fuses again is the best. If they really are good you have a short somewhere.
 

62Blazer

Senior Member
Joined
Dec 11, 2019
Posts
1,069
Reaction score
1,258
Location
Midwest
Ram Year
2016
Engine
6.4
Just to clarify when you say the fuse is good and you are not getting power back to the plug this was verified using a test light or multimeter? I've had fuses that looked okay but had a break in them and weren't transferring power. Also want to make sure you aren't just plugging in the harness and assuming there is no power at the trailer plug because the back up lights don't come on. Could be a bad wire harness that came with the rack.
 
OP
OP
R

Ramtop

Member
Joined
Jul 23, 2014
Posts
47
Reaction score
27
Ram Year
2019 Ram 2500
Engine
6.4L
Tried 3 different fuses, definitely no power using tester on the original wiring harness to the trailer plug without the new harness plugged in
 

Socalramfan

Senior Member
Supporting Member
TOTM Winner
Joined
Feb 12, 2017
Posts
4,271
Reaction score
5,104
Location
Huntington Beach
Ram Year
2011 Big Horn
Engine
4.7
It was plug and play, no issues at all on the install, and not a single issue to date. It’s 2 years old. Covid got costly, lol. I added the side rails several months ago.

For what it’s worth, here’s how I would approach it:

1. Before you even connect the pigtail they provided to tap into your hitch wiring…… take a test light and check each led at your factory connection and makes sure all leds receive power accordingly. Get someone to sit in the Ram to step on the brakes, put it in reverse, turn signals etc. That way you’ll have a starting point to base things on.

If there’s no power…. You found where the issue could be.

If part 1 checks out, then proceed.

2. Attach the pigtail they supplied to where it connects at the trailer hitch area. Next, do the same checks you just did to the factory receptacle but to the other end of the pigtail. The end that will get connected to the rack itself.

Again, if there’s no power on a particular led then it’s likely within the pigtail itself.

If part 2 checks out, proceed again.

3. Connect the remaking end of the pigtail to the connection from the head rack. Now just check all the functions and hopefully all works.

If not, then at least you’ve narrowed it down to a connection with ing the rack itself.

Make sure all connections are secure and tight, and as mentioned, fuses are good.

If you don’t have success with this, get back to me and I’ll help you further.

I have a feeling it’ll work, and you’ll love the rack :waytogo:
 

crash68

ACME product engineer
Staff member
Administrator
Supporting Member
Joined
Mar 20, 2016
Posts
10,704
Reaction score
16,709
Ram Year
2015
Engine
3.0 EcoDiesel
Did that and have no power coming to the rear so I was hoping someone knew where else to look for the problem.
Have someone start the truck and put it in reverse and check for power on one of the fuse terminals for the trailer reverse circuit. If you have power there then start inspecting the wiring harness to the back of the truck, you need to pull the driver's front wheel well liner out as people have found issues with the wiring harness where it routes around the frame.
I've attached a wiring diagram, it might not be the exact one but it's probably close enough give you an idea if the fuse #s match.
 

Attachments

  • TRAILER-TOW-SYSTEM.pdf
    334.8 KB · Views: 10

LouM

Senior Member
Military
Joined
Sep 8, 2016
Posts
548
Reaction score
563
Location
Greeenwich/Easton upstate NY
Ram Year
2015 Ram Ecodiesel crewcab old/ now 2019 Laramie Hemi
Engine
eco diesel old / now Hemi missing the eco's mileage
Using the wiring diagram from above I would say to look for power to fuse 28, then the relay.
 

crash68

ACME product engineer
Staff member
Administrator
Supporting Member
Joined
Mar 20, 2016
Posts
10,704
Reaction score
16,709
Ram Year
2015
Engine
3.0 EcoDiesel
Using the wiring diagram from above I would say to look for power to fuse 28, then the relay.
If you read my post, I specified that he needs to have someone put the truck in reverse before checking for power at the fuse.
 

Brian2081

Senior Member
Joined
Jun 4, 2019
Posts
390
Reaction score
229
Location
Weatland Michigan
Ram Year
2016
Engine
5.7
Check the harness behind the left front wheel liner. The harness runs around the left front cab mount and has a tendency to chafe through a wire or two.
 
OP
OP
R

Ramtop

Member
Joined
Jul 23, 2014
Posts
47
Reaction score
27
Ram Year
2019 Ram 2500
Engine
6.4L
Thanks everyone. This will my project this weekend if I don’t run out of time
 

jr27236

Senior Member
Joined
Nov 11, 2019
Posts
421
Reaction score
319
Location
New York
Ram Year
2016
Engine
5.7 Hemi
I would do as @Socalramfan said to do. If with out the back rack harness and you have power then it's the harness that is wired wrong. I have seen regular trailer plugs come this way and needed to be rewired different then the package said.
 
OP
OP
R

Ramtop

Member
Joined
Jul 23, 2014
Posts
47
Reaction score
27
Ram Year
2019 Ram 2500
Engine
6.4L
I had the truck back to the dealer for some warranty work today and had them check it out. Turns out, something is wrong with the wiring harness from the cab to the bumper that feeds the trailer plug so they are ordering a new one under warranty.
 

Latest posts

Forum statistics

Threads
194,927
Posts
2,864,183
Members
155,296
Latest member
VLG6963
Top