How to wire and configure the AUX switches in a 2019+ Ram pickup 

Ram didn't make this easy, that's for sure. I couldn't have figured it out without the help of multiple people on the hdrams forums, especially brutal_ho, iron byron, and jimmy07.

Ha! Ditto!

Which one did you use to get power off of?

@@brandenmulder7878 I was able to use AUX1 to switch on the power to my fuel pump in the bed of my truck. I don’t think I could have accomplished this without your RU-vid tutorial. I am sure that if I had reached out to a Chrysler dealership for help they would have struggled and it would have cost me a great deal of money. Again, many thanks.

You're welcome!

Thanks for the kind words. I have some more videos that I've been working on.

Glad it helped!

That's great! We are currently traveling all over the United States with our fifth wheel.

@@alstuart currently near Wickenberg AZ waiting for our Camp host spot to open in Oregon. Is that a 27-5L?

@@TheBuddy1939 Yes, 27-5L. We really like it.

Thanks! I just updated the video description with a link to a PDF document that contains more examples.

i know a lineman when i see one.

@RJT21 Thanks. I will update that in the final version.

I agree that it's easiest just to tap into one of the aux connectors under the hood and run a wire to the back for rear lights. I also heard that they made some changes to the 2022 model that make it , but I don't know the details.

I ordered my truck with the AUX switches installed at the factory. I don't know the part number, sorry. I believe I saw some posts on hdrams.com about adding the switches. Try this post. hdrams.com/forum/index.php?threads/diy-add-aux-switches-to-19-ram-2500-laramie-6-7l.13229/page-4#post-294649

For an interior negative, I installed a negative bus bar high up in the footwell on the driver's side and connected it to an existing ground that was exposed near the driver door hinge. I can upload a video tomorrow showing it if you reply and say you need it.

I bought the aux switch bank with the truck as a factory option.

Starting in 2021, Ram improved the AUX switch design. They added a ground wire inside the cab, and they added more passthrough wires into the cab. I don't know which battery the aux switch power comes from, but I can try to research during the next week. Here is a great video on the 2021+ AUX system. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6seCDodwohg.html&feature=share8

You can cut the loops, but it will kill the power at the rear bumper. You can tap onto the loops if you want to maintain power at the rear. After I made this video, I bought three small bus bars off Amazon. I cut the ignition loop and connected both wires to the same busbar. I cut the battery loop and connected both wires to the same bus bar. I then created a ground busbar. All three bus bars are secured underneath the floorboard carpet behind the pedals where my feet never touch. The bus bars have covers so the posts don't touch the carpet. This setup maintains ignition and battery power to the rear of the truck while also giving me ignition and battery power in the cab with a common ground. I connected my dash cam to the bus bars, and everything works great with the ability to power other devices later. I recommend you use an inline fuse for each powered device connected to a bus bar.

Yes, it's documented in TSB 08-031-20 which states, "The upfitter auxiliary fused wires are not populated on the rear of the chassis wiring harness equipped with Instrument Panel (IP) auxiliary switches. The wires are located on the right side of the rear chassis cross beam, above the fifth wheel."

For my 2019 3500, the wiring kit part number is 68398184AB. The description is, "KIT, Auxiliary Power Distribution Center" so you can look it up for your truck year/model.

it is not necessary to run the additional fuse, but keep in mind your lights might need a fuse smaller than the 40 amp fuse. In that case, you can either replace the 40 amp fuse with a smaller one, or use the inline fuse. that's the right amperage as I demonstrated in the video

@@markruddle4252 It's one of the pigtail wires that came in the AUX wiring kit which is part number 68398184ab

@@alstuartgotcha thank ya. I need those spade connectors. The aux buttons were already installed.

The upper right port on the light gray connector is a ground. The lower right port on the light gray connector is the pass through port that goes back into the cab. That's why you have 8 ports and 6 switches.

The beer is at my house, and you're welcome to come partake!

@@alstuart FREE BEER!!!🍻 🍻🍻🍻

I believe you could ignore the blue wire because they are typically attached to a rocker switch. I would connect the red wire to the output of the aux port. Connect the black wire to a ground.

@@alstuart turns out it’s a low amp second circuit for back lighting

I believe it has something to do with the PTO option on the transmission, but I never did make that video. Sorry.

One of the PDF documents in the video description says the part number for the kit is 68398184. Please call a dealer and confirm.

@@alstuart thank you

The part number for the wiring kit is 68398184AB. I do not know the part numbers required to install the power distribution box under the hood. I did see some discussions about retrofitting the power distribution box on HDrams.com/forum.

I will give you a detailed answer, but first I need to know the following: 1) What is the model year of your truck? 2) Do you want to be able to turn on the plow light when the truck ignition is off? 3) What size fuse is required for the plow light?

​@@alstuartit's a 2020 Ram 2500 with the aux switches installed from the factory. Id like the light to shut on and off with the ignition. It's a Buyers Products LED warning light and only draws 2 amps @12v, 24watts.

@@billgammon8734 I wouldn't install a relay because Ram has already installed relays for each of the AUX buttons. Each AUX button supports up to 40A, depending on the fuse. I recommend the following: 1) Install the pink/brown pigtail in the upper left port #1 of the dark-gray connector under the hood. 2) Install the violet/yellow pigtail in the lower-right port #4 on the light-gray connector under the hood. 3) Splice the two pigtails together. 4) Install the gray Jumper into the port under the dashboard near the parking brake (see @10:29 in the video). 5) Splice a 12 gauge red-colored wire onto the end of the violet/yellow wire that comes out of the gray connector under the dashboard. Run the red wire to the location of the 12v lighter receptacle under the rear seat. 6) Connect an inline mini-blade fuse to the red wire BEFORE the 12v lighter receptacle. Most 12v lighter receptacles are rated for 10A, but check your 12v lighter receptacle requirements. 7) Connect the inline fuse to the positive terminal on the 12v lighter receptacle, and find a suitable ground location for the negative terminal on the 12v lighter receptacle. 8) If your plow light doesn't have its own fuse, I recommend installing a 3A inline mini-blade fuse between the 12v lighter receptacle and the light. This way, the lighter receptacle has its own 10A fuse, and the light has its own 3A fuse. This enables you to plug other devices into the 12v lighter. 9) Under the hood, there is the AUX fusebox as shown @5:01 in the video. From the factory, a 40A fuse is installed for AUX1. I recommend switching to a 20A fuse. You need a LP JCASE (low profile) fuse that is 10mm x 12mm x 16mm. In the video, I incorrectly say you need a low-profile MCASE fuse, but it is actually a low-profile JCASE fuse. On Amazon, you can get an assortment of 40 normal and low-profile JCASE fuses from the vendor named BIOFUSE for about $30. 10) Lastly, you will need to configure AUX1 button behavior in the commercial settings. The type needs to be "latching." The power source should be "ignition." The last state option should probably be "on" so you don't have to press the AUX1 button every time you start the truck. Please let me know if this needs clarification. Thanks, Alan

You're absolutely awesome, man! Thank you!

Everything worked perfectly! Like in your video, my dark grey connector also was missing the little clip.

For my 2019 3500, the wiring kit part number is 68398184AB. The description is "KIT, Auxiliary Power Distribution Center" so you can look it up for your truck year/model.

@@davidbates3887 I want to do that so bad. Make a YT video of it!

@@alstuart I would like to but I am not too sure how to do that! 😆

For my 2019, the part number for the wiring kit is 68398184AB. I believe in 2021 the part number changed because the pinouts changed a little bit.

I do not know how the 2018 AUX system is wired, sorry.

it's probably fine if it won't come back out

Yes, you can configure it so one AUX button controls one set of rock lights and another button controls a different set of rock lights.

There is a technical service bulletin (TSB) for the 2019 Ram trucks that says they forgot to install the rear wires on some trucks. It is TSB 08-031-20 which says, "The upfitter auxiliary fused wires are not populated on the rear of the chassis wiring harness equipped with Instrument Panel (IP) auxiliary switches. The wires are located on the right side of the rear chassis cross beam, above the fifth wheel." My truck suffered from this problem. I know your truck is a 2021, but maybe it has a similar problem. You could locate the wires at the rear of the truck by using a toner. Connect the toner to the upfitter wiring harness under the dashboard by the parking brake, then use the toner wand at the rear of the truck by the cross beam to find the wire that is attached to the toner.

@@alstuart thanks Alan. Been looking for them like crazy. I did notice the extra wires on the right side but didn’t think it was. Will check if they are.

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