Finding the "ignition" side of my trucks electrical system

Garypowell · Feb 1, 2016

I have my pump installed for my Aux Tank but need to complete the electrical side.

Every so often I see of someone writing, "I hooked it to the ignition side so it will only work when the truck is running".

I understand (and want) the concept.....but where in the world do you find this magical spot? I don't really want to break any wires would like to find a place to attach my hot wire.

For my other gadgets (GPS, TPMS, Truck bed lights) I have a #14 wire going to both terminals of the battery and then to a waterproof box where I have a fuse block, etc.

But the more I think of this transfer pump I don't want it accidentally turned on as my understanding is it can ruin the pump if you let it run dry too long. I have it all set up to work through my garage door opener spare buttons which could easily be hit by accident.

Thanks,

MTPockets · Feb 1, 2016

There are probably several spots, but I know the wires to the trailer connection are only hot when the ignition is on. I tagged into mine when I added the little booster antenna for my tire pressure monitors...

cookie · Feb 1, 2016

You can find a switched fuse in your fuse box and add one of these. I did and it works great.
It's called a fuse tap.

Peace
Dave

hoefler · Feb 2, 2016

Don't know about the GM, in my Ram I tapped into the switched outlet/cigar lighter in my console.

Garypowell · Feb 2, 2016

Thanks all. Fuse tap....go figure. Always amazes me what people think up. It does not amaze me the help I get here. I count on it.

Once ce I get this working I'll write it up.

Gary

Bob&Patty · Feb 2, 2016

Gary, there is a panel to left of the steering column on the firewall that has places that are "Hot" with "key on". But I need to find the place that sells those. Then I don't have bore a hole in the firewall for my air bag setup.

Dave, who sells the fuse tap???

cookie · Feb 2, 2016

Bob&Patty said:
Dave, who sells the fuse tap???

Here ya go mi amigo. Fuse Tap.
Be aware of the different form factors. ACN, ACT, ATO bla bla bla. But you know that already.

Peace
Dave

Garypowell · Feb 2, 2016

Bob,

If you have the time there seemed to be a bunch on line....and nice price too. Being in a hurry (next trip in 2 weeks) I picked one up at Advanced Auto. My guess is any chain will have them. I forgot to look at the form factor like Cookie said.....but got lucky and picked the right one.

Gary

Bob&Patty · Feb 2, 2016

Gary and Dave....thanks. I will try NAPA in the AM.

Sniper · Feb 3, 2016

Bob&Patty said:
Gary, there is a panel to left of the steering column on the firewall that has places that are "Hot" with "key on". But I need to find the place that sells those. Then I don't have bore a hole in the firewall for my air bag setup.

Dave, who sells the fuse tap???

O'reillys carry's them for sure. I just bought a few of them 2 weeks ago when I was installing a gauge pillar. They work great.

Lynn1130 · Feb 3, 2016

I don't see it mentioned here so I will. Be mindful of the amp rating of the fuse you are taping and the total amp draw of the items you are adding to that fuse.

The old standard method I use is a VOM and the key on/key off routine. But more recently I have found that someone else has probably done what you want to do and then posted the info on the Internet someplace so a search for what you are looking for will turn up the results and save some trial and error.

dave10a · Feb 3, 2016

I believe GM has a blog site like Ford. On the Ford site there are good recommendations for this and I suspect the same is true with GM and Dodge. The other alternative is contact a good GM dealer for consolation. Depending on the Aux tank system, Ford recommended using one of the upfitter switches.

Bob&Patty · Feb 3, 2016

I am confused as to the pix Dave posted. It appears to have a place for 2 fuses. So, is one place for the fuse you need to add and one for the normal fuse in that spot? That would be great. My air compressor for my air bags probably only draws 5 amps. My issue with the air compressor was...if you left it connected to B+ all the time it would kill the batteries in a week if you did not drive the truck. An "Air Lift" auto leveling system checks for level every 45 seconds and draws a 1/2 amp every time.

cookie · Feb 3, 2016

Bob&Patty said:
I am confused as to the pix Dave posted. It appears to have a place for 2 fuses. So, is one place for the fuse you need to add and one for the normal fuse in that spot? That would be great.

That is correct Bob.
And the wire will power your new device.

Peace
Dave

Sent from my SM-G900V using Tapatalk

Sniper · Feb 3, 2016

Bob&Patty said:
I am confused as to the pix Dave posted. It appears to have a place for 2 fuses. So, is one place for the fuse you need to add and one for the normal fuse in that spot? That would be great. My air compressor for my air bags probably only draws 5 amps. My issue with the air compressor was...if you left it connected to B+ all the time it would kill the batteries in a week if you did not drive the truck. An "Air Lift" auto leveling system checks for level every 45 seconds and draws a 1/2 amp every time.

Yes that is correct. One spot is for the current fuse, and the other is for the new component line out. The only thing I ran into was I had to trim the fuse cover because of the "stacked" design, but my fuse box is behind an interior trim cover as well, so you can't see it. You maybe able to find a spot in the fuse/relay box under the hood as well.

Bob&Patty · Feb 3, 2016

I will install it in the under hood fuse panel. Room should not be a problem. Thanks Dave for the info.

Garypowell · Feb 3, 2016

I had a little time to poke around while I was having a mobile wash service take care of the Rig. The real fun of waxing starts tomorrow.....

I pulled the cover off of the fuse box and certainly saw several fuses I could replace with the fuse tap. But there were also dozens of other spots that did not have fuses in them. No time today but thought the best of all worlds is if one side of each of these holes is hot.....I won't need to displace a fuse just use a virgin spot.

I was going to do most of the install tonight when I got home but left my volt meter at the rig and will get it tomorrow.

I also discovered the wireless relay I am going to use, which is already set up to work off of my garage door buttons (one for on and another for off), when deenergized turns the relay off. As I was thinking this over last night it occurred to me me that if it did not work that way....then as soon as the truck was started again the pump would turn back on.....which is not what I want.

Gary

Bob&Patty · Feb 4, 2016

Gary, if your '15 is like my '13...good luck finding an empty spot for key on only.

Garypowell · Feb 4, 2016

Bob....I didn't. In fact at closer examination my fuse tap is for the medium size fuse for lack of a better description....and there are precious few of those kinds of "holes" in my 15 fuse block. In fact there are no empty spots where I could try my idea.

So I went back to finding a miscellaneous spot that I felt I was happy to work with. There where four fuses that had to do with the trailer (like brakes, back up lights, etc) so I picked the one for back up lights first. I could not get any power no matter which way I turn I turned. I had figured out that power only comes in on one leg.

I am not sure what I am doing wrong. I have a dummy plug for RV that I power my air pump with....that made no difference. But then the dash never said I had a trailer hooked up so I am probably fooling myself that it would work.

I think my next step is to go back and get a smaller tap. There are lots of those kinds of fuses.

And I did try all this key on and key off....still no luck.

If anyone has an idea let me know. But once I get a smaller tap I'll have more of a variety to hook into.

Lynn1130 · Feb 4, 2016

Gary,
If I understand what you are doing. The backup lights will only have power when the transmission is in reverse. Good for backup camera hookup but not much else. That won't help you. There should be two fuse boxes. One on the drivers side dash and one in the engine compartment drivers side. Check the fuses for the cig lighter, rear window defroster, and sunroof. Those are high amp on/off. The spots that have no fuses also do not have fuse holders because they are items that were not installed at the factory.

Finding the "ignition" side of my trucks electrical system

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