Ign Power Only

pchrist · December 5, 2009

Does anyone know where i can tie into an power line under the dash or in the interior fuse box for a some power? I am looking for something that is only on when the ignition is turned.

TY in advance!!!

Hubie · December 5, 2009

Does anyone know where i can tie into an power line under the dash or in the interior fuse box for a some power? I am looking for something that is only on when the ignition is turned.

TY in advance!!!

X2 on that one, also where under the hood can I tie into and only have power when the ignition is on? Oh and its for the NBS.

jpk · December 5, 2009

Tap any relay terminal marked #30. That should be switched ignition power. I found one in the main power distribution center under the hood for my fog lights and on the dash-end panel for my XM radio. I have a GMT800 though, so I don't know how the newer ones might be different

dlewis1111 · December 6, 2009

Does anyone know where i can tie into an power line under the dash or in the interior fuse box for a some power? I am looking for something that is only on when the ignition is turned.

TY in advance!!!

using a multimeter, set it for DC voltage and ground the black lead. With the ignition on, test probe some of the unused circuits. Find 12v, and then check again with the ignition off (keeping in mind the possible 10 min key off power). If it is not present with the key off, then voila.

Wires · December 8, 2009

I found power under the dash in my GMT900. There was ignition power for the power seats or something like that. I couldn't find any ignition type sources in the fuse block.

That's where I wired my GPS to (and it saved the trouble of getting power through the firewall.)

pchrist · December 8, 2009

Do you know where you tied into that line?

mfennema · December 8, 2009

Search on this forum for RAP (Retained Accessory Power). In the 07+ trucks you can find a power source like this in the box under the dash behind the brake pedal.

Wires · December 9, 2009

I don't remember exactly. Just started probing that junction box with a voltmeter. I believe the wire that I tapped into was "yellow", typical for ignition power.

Wires · December 10, 2009

I don't remember exactly. Just started probing that junction box with a voltmeter. I believe the wire that I tapped into was "yellow", typical for ignition power.

I was over at the Denali Truck forum, and they have a copy of the electrical service manual for the GMT900's. According to it:

"Locate the power supply harness under the instrument panel near the center of the vehicle. The wire bundle consists of six blunt cut wires, two red/white (battery hot), two black (ground, one light green (Ign Hot) and one light blue (Ign Hot)."

Just grab one of the black wires and a light green (or light blue), and hook onto that. Nice clean install.

The combination of power out of one of the bat wires + one of the ign wires needs to be less than 21Amps.

mfennema · December 11, 2009

Let us all know if you find that and where you find it. I have looked and never found it myself.

Wires · December 11, 2009

Let us all know if you find that and where you find it. I have looked and never found it myself.

How hard could it be?

I know it took me a bit just to find the trailer brake harness, even when I knew exactly where to look. They seem to tape/hide those things pretty good.

I have a center console, so it would be even harder to find.

jrjohnson966 · December 22, 2009

I was unable to locate the wiring bundle consisting of the 6 blunt cut wires which are supposed to be located under the instrument panel near the center of the vehicle. After much reading on this site, I was able to locate a source for switched 12v power under the dash. I am now using it to power my Sirius unit and have had no problems.

Here is a link to the information that solved my problem:

http://www.gm-trucks.com/forums/index.php?...hl=12v&st=0

There is a picture on this message, about 3/4 of the way down on the first page, which has an arrow pointing to the location of a 12v switched power source. As it states, the top left post is the 12v switched.

I connected to this post using a wire that has an in-line fuse, connected to a ground, and now have switched 12v power.

Hope this helps.