Using the HD 3500 Auxiliary Switches

[Aggie12]

OK: 2024 Ram 3500 with the Snow Chief package: I have 6 auxiliary switches at my disposal, and want to add front auxiliary driving lights that are triggered by the high-beams. Looking for well-informed input and confirmation that I'm not going to burn my truck up !

These are LED driving lights that come with a wiring harness including relay, and the harness includes a fuse for 10 amp power supply.

I plan to use one of the truck's auxiliary switches through the Auxiliary Power Distribution Center under the hood, to power the LED kit's 10 amp power supply. I'll reconfigure this control relay in the PDC to fuse it for 10 amps. This way I can remove the separate fuse that came with the kit; the 10 amp supply feeds terminal #30 on the light kit's relay.

I then plan to wire the kit's relay so that it's driven/controlled by the high-beam headlight circuit - I plan to scotchlock a wire to the driver's side high-beam wire and seal this with Liquid Tape. This will go back to terminal #85 on the kit's relay.

So, on the kit's relay, now: #30 is power 'in' from the RAM's PDC, #85 is the high-beam triggering signal, #87 #86 is the ground, #86 #87 is the power supply out to the driving light.

This way, when the Snow Chief auxiliary switch is 'off', there is no power to the driving light relay - it's dead. When the Snow Chief auxiliary switch is 'on', the relay is powered and if the high-beams are switched on, the relay sends power to the driving light.

Does anybody see any problems with this setup? First time fooling with RAM's PDC. Appreciate all input, thanks. I'll feed back the results when I complete the project.

 

[Badger 13]

Just my opinion, but as finicky as the electronics are on these trucks I would not mess with PDC. I would just wire any of your accessories through the auxiliary power distribution center the truck came with. And I would NEVER use a "scotchlock" in any wiring system. Again, just my opinion, and you know what they say about opinions..

 

[Aggie12]

Thanks Badger 13. The Auxiliary PDC is what I was referring to, it comes with relays and fuses already wired in place and assigned to the 6 auxiliary switches that are on the dash. As for not using Scotchlock quick splices, what would you recommend? Is there another product available to tap into existing wiring, or is it still just splicing the wire and soldering in the tap? Looking at the harness, there's not a ton of room there to work with. I don't have the 'Upfitter's Module', which includes an auxiliary high-beam port, so I can't tap in there. If there is another option I'd be grateful for a steer, thanks!

 

[mtnrider]

I wired my aux lights to come on with the high beams and also a stand alone switch if I chose. I wired mine to the Highbeam output at the BCM, BUT one thing I did was add diodes to those lines so I am not back driving the highbeam circuit. I think that is critical in these computer controlled vehicles so you don't damage any of the driver circuits or cause faults.

.

 

[Aggie12]

mtnrider, thanks for the reply. I'll read up on this. I think my BCM might be in the cabin, so this would mean a firewall penetration. Ugh! My last truck was new 27 years ago, and things were a little bit simpler when customizing. If you could point me to a handy resource on how you did your rig up, and maybe on diodes, I'd be grateful, thanks. I can see I have some more work to do.

 

[crash68]

#30 is power 'in' from the RAM's PDC, #85 is the high-beam triggering signal, #87 is the ground, #86 is the power supply out to the driving light.

You might want to check the wiring terminals, typically automotive relays the coil terminals are #85 & #86.
The power from the truck Auxiliary switches would goto #30 and #87 goto the LED lights

As for taping the high beams, you'll want to use both the positive and negative to the relay coil, don't use the body ground.

 

[Aggie12]

Thanks crash68, I'm using the manufactured harness that came with kit, and the relay that came with it is already plugged into it - I haven't changed the terminal assignments. The power is coming into #30 from the truck's auxiliary switch, via the auxiliary PDC, and #87 drives the auxiliary lights - I had a typo in the original message (corrected now).

Sorry if this is a stupid question, but: Why not use the body ground?

 

[crash68]

Why not use the body ground?

Using a body ground could cause some weird voltage biasing within the BCM causing a fault to be reported and/or it will turn that circuit off.

 

[Badger 13]

Aggie12, there are a lot of good videos out there on connecting wires. As you mentioned, having the room to get into and do some make it difficult at times. I would search the inter web and look at a few methods, and find one that works the best for you. Not to blow off your question, but a video can probably show you better then I can explain it. You seem to be on the right track with your plan, so I wish you luck with it.

 

[Wild one]

Just throwing this idea at you,but have you considered totally bypassing the trucks lighting circuit,and use an old school floor mounted dimmer switch to control the driving lights.Just use it as an On/Off switch to control your relay.

Amazon.com : floor dimmer switch

 

[Timsdually]

Sounds like programming.
I had a '17 that was shifting erratically. Luckily it was still under warranty.
Took it in, they said it needed to be re-programmed.
Got it back and shifted beautifully from there on out.

 

[Aggie12]

@Badger 13, thanks - I've gone a looked for a few videos, I want to understand how a protective diode is placed into a circuit, and also want to know what kind of diode should be used - but oddly enough, I'm having trouble finding such videos. There's quite a few of these videos out there on wiring in auxiliary lights, but none of them go into tapping into the BCM or using diodes. I've done this before myself on older vehicles I've owned and it worked fine, just tapping into the high beam circuit directly at the head light to drive the relays. Now, with what I'm reading about modern automotive circuitry being so 'particular', I'm a little reluctant until I learn more.

@Wild one, thanks, I hadn't thought of that option. I really want to control the auxiliary driving lights with the headlight dimmers for ease of use and ergonomics though, governed by a primary power switch so I can use them only when preferred.

I appreciate all the inputs - thanks gents.

 

[Timsdually]

Sounds like programming.
I had a '17 that was shifting erratically. Luckily it was still under warranty.
Took it in, they said it needed to be re-programmed.
Got it back and shifted beautifully from there on out.

WT??
How did this end up here?
This was response to the guy with the 2024 with horrible sound.

 

[Badger 13]

With my 70's, 80's and 90's Dodge trucks wiring accessories were easy. Going to a 4th gen from a 2nd gen, wiring was not like the "old" days. To avoid all electrical issues on my truck, I went with a Spod switch system. I know this doesn't answer our question, but just saying. Maybe give the folks at Headlight Revolution a call, they have been good at answering questions in the past, plus they have a lot of install videos. Oh, and I have no affiliation with HR.

 

[Wild one]

@Badger 13, thanks - I've gone a looked for a few videos, I want to understand how a protective diode is placed into a circuit, and also want to know what kind of diode should be used - but oddly enough, I'm having trouble finding such videos. There's quite a few of these videos out there on wiring in auxiliary lights, but none of them go into tapping into the BCM or using diodes. I've done this before myself on older vehicles I've owned and it worked fine, just tapping into the high beam circuit directly at the head light to drive the relays. Now, with what I'm reading about modern automotive circuitry being so 'particular', I'm a little reluctant until I learn more.

@Wild one, thanks, I hadn't thought of that option. I really want to control the auxiliary driving lights with the headlight dimmers for ease of use and ergonomics though, governed by a primary power switch so I can use them only when preferred.

I appreciate all the inputs - thanks gents.

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[Choupique]

Man that seems like a lot of BS when you already have the aux switch panel and the box and connectors under the hood. Just wire the accessories into the aux plugs and use them that way. Easy, no mess, no splices, works great.

 

[68PowerWagon]

Just throwing this idea at you,but have you considered totally bypassing the trucks lighting circuit,and use an old school floor mounted dimmer switch to control the driving lights.Just use it as an On/Off switch to control your relay.

Amazon.com : floor dimmer switch

WOW! I haven't seen one of those in a long time. I was trying to explain it to my teenage son a few weeks ago. He was nodding his head but I don't think he really understood.

 

[Wild one]

WOW! I haven't seen one of those in a long time. I was trying to explain it to my teenage son a few weeks ago. He was nodding his head but I don't think he really understood.

I still prefer the old floor mounted dimmer switch over a stalk mounted dimmer,lol

 

[leroys73]

What I have done on motorcycles with CAN BUS is to install a fuse block with a relay. I used something that was on when the "key" was on as a trigger for the relay to the fuse block which was powered straight from the battery after the relay was activated. Then another relay for the driving lights triggered by the high beam. I did not have any problems. That should work on the RAM.

 

[Aggie12]

Wild One, many thanks for the links to those videos, much appreciated.