What's new
Ram Heavy Duty Forum

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

Need wiring help... Halogen to OEM LED tails

JTS1285

Member
Messages
35
Reaction score
12
Points
8
Hi all... Newbie here looking for a little help..
I am wondering if anyone might possibly have access to some pin out diagrams for a 2021 Ram 2500 Big Horn with halogen tail lights?
And also a pin out for the same year/trim with the factory LED tail lights without BSM?
I'd like to buy the 12 pin connectors, de-pin from the old 6 and into the 12 but not sure which are what and what goes where...

If anyone can help a guy put I would greatly appreciate it....
 
Last edited:
Hi all... Newbie here looking for a little help..
I am wondering if anyone might possibly have access to some pin out diagrams for a 2021 Ram 2500 Big Horn with halogen tail lights?
And also a pin out for the same year/trim with the factory LED tail lights without BSM?
I'd like to just buy the 12 pin connectors, de-pin from the old 6 and into the 12 but not sure which are what and what goes where...

If anyone can help a guy put I would greatly appreciate it....
I'm pretty sure you can buy the oem LED jumper harnesses, your truck should have the correct wires up to where the jumper plugs in. You could re pin if they use the same style of pins but would still need to add the fault sense wire from the jumper harness plug to the taillight. And then enable LED tails with alfaobd or jscan

s-l1200.jpg
 
Last edited:
Hi all... Newbie here looking for a little help..
I am wondering if anyone might possibly have access to some pin out diagrams for a 2021 Ram 2500 Big Horn with halogen tail lights?
And also a pin out for the same year/trim with the factory LED tail lights without BSM?
I'd like to just buy the 12 pin connectors, de-pin from the old 6 and into the 12 but not sure which are what and what goes where...

If anyone can help a guy put I would greatly appreciate it....
 
I am aware that there are harnesses out there that can be used but I'd rather buy the 12 pin connector ends and spend 15 minutes a side and put that $100 towards the tails or new tires...
Retro shop has these plug and play harnesses and no BCM flash is required..
What seems interesting to me is most of the aftermarket harnesses like retro shops have 5 wires going into the male 12 pin connector. The taillights without BSM have 6 pins sticking out the female connector?
 
Last edited:
I am aware that there are harnesses out there that can be used but I'd rather buy the 12 pin connector ends and spend 15 minutes a side and put that $100 towards the tails or new tires...
Retro shop has these plug and play harnesses and no BCM flash is required..
What seems interesting to me is most of the aftermarket harnesses like retro shops have 5 wires going into the male 12 pin connector. The taillights without BSM have 6 pins sticking out the female connector?
It's because they are not using the fault sense wire


Screenshot_20240819_060104_Chrome.jpg
 

It's because they are not using the fault s
It's because they are not using the fault sense wire


View attachment 76224 Good to know..I appreciate you confirming this.
 
Super Joe is correct I did same research ! When I did mine but ended up just ordering the harness

 
Super Joe is correct I did same research ! When I did mine but ended up just ordering the harness

I looked through your post and I don't blame you at all for buying the harnesses for that set up you had. I would have also. I just can't see spending over $100 on adapter harnesses when I can unpin and repin 6 wires in two $7 connectors for the all in price of $18 shipped and 30 minutes.. repinning terminals is usually pretty easy. And I like a challenge.
 
Last edited:
I looked through your post and I don't blame you at all for buying the harnesses for that set up you had. I would have also. I just can't see spending over $100 on adapter harnesses when I can unpin 6 wires and repin 5 of them in two $7 connectors for the all in price of $18 shipped and 30 minutes.. repinning terminals is usually pretty easy. And I like a challenge.

I started a thread at ramforum back when I installed the 2019+ tails in my 4th gen including getting the blindspot to work. There are a lot of connector housing and pin part #'s in that thread in case you don't have the correct one.


Housing

Pins


 
Last edited:
I started a thread at ramforum back when I installed the 2019+ tails in my 4th gen including getting the blindspot to work. There are a lot of connector housing and pin part #'s in that thread in case you don't have the correct one.


Housing

Pins


These connectors are definitely better priced on this site... will be buying from here and thanks for the recommendation.
I went and looked through your old write up. Sure would have been nice if that website still worked for the diagrams but I'll just have to stab the 6 pin and figure out what is what..
 
These connectors are definitely better priced on this site... will be buying from here and thanks for the recommendation.
I went and looked through your old write up. Sure would have been nice if that website still worked for the diagrams but I'll just have to stab the 6 pin and figure out what is what..
https://connectorrepairkit.mopar.com/

You can look up any connector on any FCA/Chrysler product for free
 
Hi all... Newbie here looking for a little help..
I am wondering if anyone might possibly have access to some pin out diagrams for a 2021 Ram 2500 Big Horn with halogen tail lights?
And also a pin out for the same year/trim with the factory LED tail lights without BSM?
I'd like to buy the 12 pin connectors, de-pin from the old 6 and into the 12 but not sure which are what and what goes where...

If anyone can help a guy put I would greatly appreciate it....
These are the 12-way connectors you will replace your existing 6-way tail light connectors with:

The wires in positions 1-5 on the existing 6-way connector will go into positions 1-5 respectively on the new 12-way connector (ie- wire from position 1 on the 6-way goes into position 1 on the 12-way, etc).
Then, you need to add a new wire to your tail light jumpers. Take a length of wire, and crimp a molex 33012-2003 terminal on one end and insert it into position 7 of the new 12-way connector. Crimp a TE Connectivity 7-1452668-1 and TE Connectivity 964972-1 wire seal onto the other end of the wire, and insert it into position 11 of the chassis side 12-way connector on the tail light jumper.

These will be the alfaobd changes:
CBC Features: LED Reverse Lamps Present- Yes

CBC Features: LED Stop Lamps Present- Yes

CBC Features: LED Rear Turn Lamps Present- Yes

CBC features: LED Tail Lamps Present- Yes

CBC config I/O Usage: Left Rear Turn Lamp Diagnostics Present - Pin F27- Yes

CBC Config I/O Usage: Right Rear Turn Lamp Diagnostics Present - Pin F31- Yes

CBC Config I/O Usage: Separated Lighting Brake Lamp Dropout- Yes
 
Last edited:
https://connectorrepairkit.mopar.com/

You can look up any connector on any FCA/Chrysler product for free
These are the 12-way connectors you will replace your existing 6-way tail light connectors with:

The wires in positions 1-5 on the existing 6-way connector will go into positions 1-5 respectively on the new 12-way connector (ie- wire from position 1 on the 6-way goes into position 1 on the 12-way, etc).
Then, you need to add a new wire to your tail light jumpers. Take a length of wire, and crimp a molex 33012-2003 terminal on one end and insert it into position 7 of the new 12-way connector. Crimp a TE Connectivity 7-1452668-1 and TE Connectivity 964972-1 wire seal onto the other end of the wire, and insert it into position 11 of the chassis side 12-way connector on the tail light jumper.

These will be the alfaobd changes:
CBC Features: LED Reverse Lamps Present- Yes

CBC Features: LED Stop Lamps Present- Yes

CBC Features: LED Rear Turn Lamps Present- Yes

CBC features: LED Tail Lamps Present- Yes

CBC config I/O Usage: Left Rear Turn Lamp Diagnostics Present - Pin F27- Yes

CBC Config I/O Usage: Right Rear Turn Lamp Diagnostics Present - Pin F31- Yes

CBC Config I/O Usage: Separated Lighting Brake Lamp Dropout- Yes
You guys have gone above and beyond to give me the info I need to get this job done.
I greatly appreciate all your help..
I will report back once I get the parts here and get them installed..
 
I got the connectors and all pins needed.. cost me $20 total with $10 of that for 2 day shipping..

Thanks again!
 
Last edited:
20240907_142356.jpg
Takes about 5 minutes to swap the connectors. Super easy. Just pull wires and put in new connector. Both are Molex MX 150 style connectors so you dont need a different style female terminal. If anyone else decides to give it a try here are the part numbers. Top bag was the 12 pin connectors and bottom bag is the cavity plugs to fill in the unused ports in the connector. 20240907_142516.jpg
 
Last edited:
These are the 12-way connectors you will replace your existing 6-way tail light connectors with:

The wires in positions 1-5 on the existing 6-way connector will go into positions 1-5 respectively on the new 12-way connector (ie- wire from position 1 on the 6-way goes into position 1 on the 12-way, etc).
Then, you need to add a new wire to your tail light jumpers. Take a length of wire, and crimp a molex 33012-2003 terminal on one end and insert it into position 7 of the new 12-way connector. Crimp a TE Connectivity 7-1452668-1 and TE Connectivity 964972-1 wire seal onto the other end of the wire, and insert it into position 11 of the chassis side 12-way connector on the tail light jumper.

These will be the alfaobd changes:
CBC Features: LED Reverse Lamps Present- Yes

CBC Features: LED Stop Lamps Present- Yes

CBC Features: LED Rear Turn Lamps Present- Yes

CBC features: LED Tail Lamps Present- Yes

CBC config I/O Usage: Left Rear Turn Lamp Diagnostics Present - Pin F27- Yes

CBC Config I/O Usage: Right Rear Turn Lamp Diagnostics Present - Pin F31- Yes

CBC Config I/O Usage: Separated Lighting Brake Lamp Dropout- Yes
what about when going from the two connector, 5 wire halogen tailights on a 2014 2500
 
These are the 12-way connectors you will replace your existing 6-way tail light connectors with:

The wires in positions 1-5 on the existing 6-way connector will go into positions 1-5 respectively on the new 12-way connector (ie- wire from position 1 on the 6-way goes into position 1 on the 12-way, etc).
Then, you need to add a new wire to your tail light jumpers. Take a length of wire, and crimp a molex 33012-2003 terminal on one end and insert it into position 7 of the new 12-way connector. Crimp a TE Connectivity 7-1452668-1 and TE Connectivity 964972-1 wire seal onto the other end of the wire, and insert it into position 11 of the chassis side 12-way connector on the tail light jumper.

These will be the alfaobd changes:
CBC Features: LED Reverse Lamps Present- Yes

CBC Features: LED Stop Lamps Present- Yes

CBC Features: LED Rear Turn Lamps Present- Yes

CBC features: LED Tail Lamps Present- Yes

CBC config I/O Usage: Left Rear Turn Lamp Diagnostics Present - Pin F27- Yes

CBC Config I/O Usage: Right Rear Turn Lamp Diagnostics Present - Pin F31- Yes

CBC Config I/O Usage: Separated Lighting Brake Lamp Dropout- Yes
@Jimmy07 is there a removal tool to take the current crimps out of the 6 way plug, or is it cut the wires out of the 6 way plug and crimp new connectors on them to put into the 12 way plug? Thanks.
 
@Jimmy07 is there a removal tool to take the current crimps out of the 6 way plug, or is it cut the wires out of the 6 way plug and crimp new connectors on them to put into the 12 way plug? Thanks.
When you are looking at the inside of the plug, the terminal locks will be secured in place by a white cap. This cap has a slot in the edge of it to pry it forward with a screwdriver.

On the 6 way connector- Remove this cap entirely. Pry it to the release position and then pry a little more to remove the cap entirely. Now you will be able to use a pick and pry down on the little locking tabs for each terminal and pull the terminals out the backside of the connector.
On the 12 pin connector- Pry on the locking cap until it pops out to the release position. No need to completely remove this cap. Now you can slide the terminals into the backside of the connector. You will hear a clicking noise when they engage the locking tab. Once you have all terminals stabbed in, push the cap back in and your done..

I recommend you do them 1 wire at a time like I did, so nothing gets mixed up. Hope this helps..
20240907_142120.jpg
 
@JTS1285 I know this is an old post but do you have any pics of the completed 12-pin connector? I'm currently doing the exact same thing to my 5th gen. Thanks!
 
@JTS1285 I know this is an old post but do you have any pics of the completed 12-pin connector? I'm currently doing the exact same thing to my 5th gen. Thanks!
This is the only picture I could find and I hadn't swapped the fault sense wire or installed the cavity plugs. The backside of the connectors are numbered 1-6 (top)and 7-12(bottom) for the different cavities. You will see these tiny numbers on the outside edges of the connector. You can use the diagram above from superjoe83 for reference to make sure you got it all correct.
If I recall correctly, the 1-5 wires on the six pin connector, go into the same corresponding cavities in the twelve pin connector. Only difference is the fault sense wire which is in cavity 6 of the six pin connector, goes into cavity 7 of the twelve pin connector. And the empty cavities will need to be filled with cavity plugs for obvious reasons.
Hope this helps!
 

Attachments

  • Screenshot_20250903_214424_Photos.jpg
    Screenshot_20250903_214424_Photos.jpg
    162.3 KB · Views: 11
Back
Top