Custom buttons in empty dash spots

Did you push wires for relay through the firewall? You don't have to poke through the firewall gromet if you put relay under the dash

I think the factory beacon light wiring actually puts the relay near the B Pillar behind the driver. Not 100% for sure, but I don't think it does it under the hood. You get the fused power from the engine fuse block in the drive footwell in the MBEC connector.

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PutUpYourDux said:

i already have a relay installed under the hood for the light bar, so it sounds like i just need to connect the trigger wire for the relay to the new beacon switch in lieu of my existing rocker switch, and then move the add-a-fuse wire to the illumination wire on the new switch. can you confirm that i just need to pick up these two parts: beacon switch (gm 15722980) and the SEO connector (delphi 12193930, currently $35 on ebay)? everything else should just be wire and solder/connectors/terminals/etc., correct? i can't find the beacon switch anywhere now. i found it on ebay a few months ago but nothing now, on any website. hopefully i can find one somewhere at some point.

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Those parts sound correct.

ok cool. thanks for your responses. the previous owner installed my light bar, but the relay is currently screwed to the side of the underhood fuse box, and the wires between the current toggle switch and the relay are run through the driver door harness rubber boot and routed up into the engine bay behind the fender. i know, it sounds half assed, but it is actually pretty well hidden and i haven't had any issues. i would very much like to re-route the wires to place the relay and all the wiring inside the vehicle, as you mentioned, BUT my light bar is mounted to the front bumper below the grille. as such, i don't think i can get away from running some wiring across the firewall. it has to be either the relay input wire from the switch (if the relay is under the hood and i draw power directly from battery) or the relay output wire (if the relay is under the dash and i draw power from your nifty SEO connector). might be best to just forego the SEO connector in my case and leave the relay harness as it sits right now.

for your setup, it sounds like you just needed that SEO connector in order to draw power for the light bar, via 1 single wire. is that correct? did you use the 30A SEO2-fused pin?

You are correct, I just needed the SEO connector for the MBEC. The one on eBay I bought came with the pins and short wires to wire it up. You might be able to buy just the connector. It's a fairly common connector and can be bought for a few dollars, but I wasn't sure if the connector from electronic's supply came with pins and all that.

It's been a while since I hooked it all up. I still have to finish off cable routing though :| I'm going to take the lazy man's method and just put a connector in the moon roof / drain and plug in the light there. Mine will go on the roof rack. Not ideal either but best I could come up with without some really custom work to the roof. Yeah from sound of it, if your light in by your bumper than you've got an optimal setup for routing cables. I actually took apart my grommet in the firewall (not recommended insane amount of work) and routed a coax cable for CB radio through it.

To your question, you can choose which fuse you prefer. There's several options in the connection there. I probed for my 2001 and found this:

Pin A - Always Hot Fused 30A from SEO2 in under hood relay center
Pin B - Not Connected
Pin C - Ground
Pin D - (FUSED??) Hot in Run & Accessory
Pin E - (FUSED??) Hot in Run
Pin F - Always Hot Fused 15A from SEO1 in under hood relay center

FYI ~ I don't recall the year on your truck. The pinout changes after 2002? I have some diagrams earlier in this thread. You'll probably want to test the pins to confirm them. I used a multi-meter and test light to do just that.

I don't recall which pin I ultimately chose SEO1 or SEO2 (you can easily use a connector key or paperclip to move the pin if you change your mind). For dash illumination, there were multiple lines on the backside of the MBEC. It's not what I wanted to do, but I spliced into one of the dash illumination wires and ran the cable to my switch. Works like a champ with dimming and everything on the dash.

I should have documented better. It took a TON of research, factory service manual (AllDataDIY), electrical shop manuals, and experimenting to get it hooked up.

thanks so much dude. mine is a 2001 too. i currently have my setup fused under the hood via an inline fuse. i have to mull whether i will keep it that way and not have to change any of the existing wiring (easy path) or whether i want to move the relay inside the vehicle and draw power from the MBEC while using one of the two SEO fuses (preferred since I am OCD like you, but more work for zero change in functionality).

thanks for the info on where you spliced for illumination. i thought you had mentioned using an add-a-fuse in the driver knee-level fuse box and tapping into the illumination circuit that way. something for me to think about. i like having a fuse in case there is a short, but your way would be cleaner for sure.

i think i remember seeing where you posted the pinouts for the switch itself. that is likely all i need if i decide to keep my relay wire as it is. just need to know ground, power, and illumination. this is what you last posted for the switch pinouts. do you recall if this is correct? if not, do you mind updating? i found a switch today on ebay (last one!) and i'm betting it is the same place you bought yours since the photo looks the same as your first post.

PIN A: Blank
PIN B: BLACK: Ground?
PIN C: White - Power? ~ Fuse SEO 1 (15A?
PIN D: Purple - Dash illumination - indicates relay active
PIN E: Gray - Reference / Ground?
PIN F: Orange - BUTTON PRESS

Should be correct. There is also a factory pinout on one of the previous posts. If your eyes are good enough you can see labels for the pins on the MBEC as well.

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hey man. finally got around to fixing my wire routing (through the firewall now instead of the door jamb) and also wired up the relay and roof beacon switch similar to you. it works great, with one caveat: their is no backlight for the switch, and the orange LED only turns on/off with the switch button when the dash lights are on. if the dash lights are off, the button activates the light bar, but the LED indicator on the switch doesn't illuminate. i'm thinking something is slightly off with the pins. here's what i connected to the switch:

PIN A: Blank
PIN B: Black - Ground
PIN C: White - Full time 12V (fuse SEO 1 - 15A)
PIN D: Purple - Dash illumination - I tied this into the illumination fuse for now
PIN E: Gray - Ground
PIN F: Orange - Trigger wire for the relay (you called this "button press")

does your switch have a backlight, meaning a light that lights up the little truck + beacon symbol on the switch face? does your orange LED always turn on when the switch is active regardless of whether the dash lights are on? would you mind popping your switch out and noting what pins your ended up using in your final configuration? i am so close, and while it is functional now, i would love to have it perfect such that the switch lights work correctly. thanks dude!

Got it figured out and mine is now 100% working. Backlight turns on with the rest of the dash lights, and the orange LED turns on whenever the switch is activated, regardless of whether the ignition is on or the dash lights are on. For anyone that may be looking for this in the future, these were the pins on the beacon switch:

PIN A: Blank

PIN B: BLACK: Ground

PIN C: White - Constant power. I used fused SEO 1 power (15A), supplied from the MBEC.

PIN D: Purple - LED indicator light (indicates when switch is active). I used fused SEO 1 power again such that the LED will come on when the switch is active even if the ignition is off.

PIN E: Gray - Backlight for the switch (little truck + beacon icon). For now, I used an add-a-fuse plugged into the dash illumination fuse spot on the driver knee fuse panel. I am upgrading my head unit soon, and I plan to pull illumination from the head unit harness (to avoid splicing into the factory harness) such that I can remove the add-a-fuse and the associated (fairly long) wire.

PIN F: Orange - Button press / trigger wire. This is the wire that activates the relay when the switch button is pressed.

Alot of great info here, nice work. Thanks Guys!