Wiring Help

[JTrac]

I got a set of Air Lift 5000 air bags and their Wireless One for my 2012 GMC 3500 diesel. I got the bags on and the wireless compressor installed in just a few hours but spent the rest of the day trying to find a way to wire the compressor. The instructions say to wire it to a wire that works only when the ignition is on. I called Air Lift and they weren't able to help me much. They did say the instructions call for it to be wired that way in case a leak is developed. The compressor will try to keep the set pressure and could run the batteries down.

I finally gave up and temporarily wired it to an open pin in the fuse box under the hood. GM certainly did a good job bundling and hiding wires. I don't think the compressor draws any power till needed so I may just leave it. Anyone know where I need to look to find a source wire that is heavy enough to match the 12 gauge wire Air Lift uses?

[Perrysburg_Dodg]

Complete 2012 wiring diagram

There should be at least 2 "IGN" on open slots in the under hood fuse box. If not find any fuse that is controlled by the "ING" on tap into it and use a relay to switch on battery power for your compressor.

But I bet there are open slots in the fuss box.

Don

[_40Fan]

Fuse 43, 48 and 55 would be ignition "on" fuses that you could use. Tap into the firewall side of any of these fuses.

[ktosv]

As mentioned, how about a fuse tap? It essentially turns one fuse location into two and has a pig tail to wire your new item to the second fuse location. I did this on two different vehicles with accessories I was adding. I got the latest one (2 years ago) at Advance Auto and it was way better than the one I used 10+ years ago. Use a voltmeter to determine which fuse's are powered when the ignition is on/off.

[BoxerPitMix]

I've hooked up several compressors. I prefer them to kick on only when my key is on.
On my '09, I wired it to a relay that draws current from my trailer charge wire (I believe the larger of the two posts on the main fuse block that generally aren't connected when you first get your truck). If you don't want to draw it from there, you could pull it directly from your battery or the stud post near the alternator.

As far as the "key on" trigger to turn on the relay, I ran off one of the accessories from the under hood fuse box. I can't remember off the top of my head which one... But the relay won't be pulling many amps, so you'd probably be safe with just about anything on there. Just check it with a test light to see what kicks on/off with the key. You can use a "fuse tap." They are available for both regular and mini (ATC, ATO, ATM) fuses. I believe you can find them at AutoZone or similar. They're all over the web, too.

And put a fuse in everything!! 🙂

HEREis a great write-up on setting up a relay on NNBS GM pickups.

[JTrac]

Thanks for the help, now I have options to consider. We are leaving on a 4K trip in a few weeks and want to have it buttoned up before we go.

[catfishmontana]

I would wire it direct to a relay then to the battery and use an upfitter switch connected to the relay. I like to have full control of everything myself. But that's just me.

[wittmeba]

Another option you might consider.

I wired our Pyro, Boost and Transmission temp gauge to my parking lights. This proved a good choice. I drive with our parking lights on almost all the time (all the time when towing) so it worked very well.

I just popped the light switch out and using a probe penlight turned the lights on/off until I found the right wire. Used a T tap and it has not failed in about 7 years.

Diagram shows 2 wires to each device and the signal cable/harness/tube for each function.

[BurbMan]

Don't splice into anything that's in a wiring bundle, a lot of stuff is run by data signals and adding something to a circuit can cause changes in impedences, etc., that can really mess things up.

Best bet is to do like you did, run a separate wire back to the fusebox. Look in the owners manual and see if there are any studs in the underhood fuse box that are designated for ignition-switched accessories. If not, you can wire to the stud post by the alternator that GM provides for connecting accessories. Don't forget to add an inline fuse.