12v switched power

[Matt]

Here's something I posted at the OS for getting 12v switched power. Comes in handy when you are adding sat radio or something else. There are alternative ways of doing this and hopefully the guy's that know them will add to this post.

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View attachment 19035

A big to May03LT for providing this to me originally.

 

[AbsoluteZero]

I used fuse 29 and a add-a-fuse in the rear fuse block. It's the Rain Sense wiper circuit. For some reason it had a 10a fuse installed even though I don't have Rain sense wiper option

 

[Blckshdw]

for migrating this over. Now I don't have to go back to the OS to reference it.

 

[The_Roadie]

I've posted this list a few times, in case you want it to be switched in different modes from the ignition switch or to use an add-a-tap gadget:

RED on the ignition switch is 12V, fused by underhood fuse #34, and feeds the following three circuits:

White is hot in ACCY, RUN, START
Orange is hot in RUN
Yellow is hot in START

RED/WHITE is another 12V, fused by underhood fuse #36, and feeds two circuits:

Brown is hot in ACCY, RUN
Pink is hot in RUN, START


If you go after the fuse block path:

On in RUN/ACCY modes only:

rear fuse #29 - Rain sensor (rare option) 10A
rear #33 - front wiper motor - 25A
rear #31 - TBC ACC - 3A

ACCY, RUN, and START:

rear fuses 47 (IGN 0)
50 (TBC IG)

RUN only mode:

front fuses 22 (IGN E)
16 (TBC IGN 1)
27 (BACKUP)
28 (PCM 1)
54 (AIR SOL)
53 (O2 A
54 (O2 B)
26 (ENG 1)

 

[Me007gold]

Whats the problem with using a T-Tap on this wire?

 

[The_Roadie]

By their very nature, t-taps damage (cut, nick, distort) some of the internal strands of the wire they're put onto. Better for a farther downstream wire if you have to use them at all, instead of these wires near the ignition switch that are at the feed ends of the vehicle's harness. The current is highest near the ignition switch, and you will reduce the reliability of the wire you're tapping into.

 

[djthumper]

Thanks for bringing this information over.

 

[Boricua SS]

great info...

although i wont be using the ignition for switched power, im adding LED strips under the dash.. so i will tap into the rear fuse block using the add a fuse approach...

 

[DDonnie]

Is there a 12v switched line going to the controller for the rear windshield wiper that could be tapped into for switched 12v on a stereo? (my lead isnt long enough to reach either fusebox and i dont want to tap into the ignition harness until i install a remote start)

 

[The_Roadie]

There is a low current 12V reference wire going to the rear wiper switch, but it's intended only to let the BCM measure the switch resistance to determine the speed. It's not a power line to connect anything heavy to. Outside the fuse blocks and ignition switch, switched power is difficult to come by. Surely you can easily solve the problem of the lead being too short, or use the proper adapter to give you switched power controlled by the data bus up at the head unit?

 

[DDonnie]

There is a low current 12V reference wire going to the rear wiper switch, but it's intended only to let the BCM measure the switch resistance to determine the speed. It's not a power line to connect anything heavy to. Outside the fuse blocks and ignition switch, switched power is difficult to come by. Surely you can easily solve the problem of the lead being too short, or use the proper adapter to give you switched power controlled by the data bus up at the head unit?

Thanks for the info, ill just extend the cable then.

 

[YOUNG]

thanks alot guys , this will help greatly with any mods i do with led strips.

 

[Dakota76]

im replacing my HU and i like the feature of the original when you shut of the vehicle the radio stays on till i open the doors
so my question. Is there a wire that will do this for me. I would like to keep this feature. Right now im tied into the brown wire that goes to my temp control unit.

Thanks DAK

 

[pejeeper]

I plan on adding an after-market stereo that requires a secondary power feed in addition to the power feed in the chassis harness. In past vehicles, I used a power window circuit with an add-a-fuse in the slot that was empty b/c the vehicle didn't have that option. My 05 TB does not have power seats or heated seats, is that a separate fuse slot that I can ad the add-a-fuse to for the stereo?

I currently have a car seat strapped in over the fuse block.

 

[Sparky]

There is a harness adapter you should get that retains all those features and provides the power wires you need.

Depending on your audio options (Onstar or not, Bose or not, etc) you'll need a GMRC-01, or a GMOS, or whatever. I have a GMRC-01 in my 02 LS.

 

[pejeeper]

There is a harness adapter you should get that retains all those features and provides the power wires you need.

Depending on your audio options (Onstar or not, Bose or not, etc) you'll need a GMRC-01, or a GMOS, or whatever. I have a GMRC-01 in my 02 LS.

Thanks for the reminder...I found this out when I was on Crutchfield looking at HUs. I didn't know that the adapter had a 2nd power lead though...

 

[Sparky]

Yup it creates one from the always on. It communicates with the data bus which is how the RAP works for windows and the radio and such. Yeah, the factory radio provides the RAP for the other stuff, go figure

 

[am-radio]

Found this thread, but was wondering if it's possible to change both (or at least one) cigarette lighter/12 volt power sockets to work only when the truck is in acc or run. The constant on is going to cause me to get a call from the wife saying the battery is dead, as she always leaves stuff plugged in to them.

 

[DDonnie]

Found this thread, but was wondering if it's possible to change both (or at least one) cigarette lighter/12 volt power sockets to work only when the truck is in acc or run. The constant on is going to cause me to get a call from the wife saying the battery is dead, as she always leaves stuff plugged in to them.

Couldn't you cut the 12v constant and run it to the brown or orange acc wire in the ignition harness? I would think those could handle the load. Could be wrong though ...