12v - Constant & Acc. On Driver Side / Elec Gauge Install (boost)

[Dat1seriesdoe]

So , i won an ebay bid the other day on a Defi BF gauge and ive installed gauges in everything ive ever owned and figured i was doing it on the 135 as well. As i searched the ENTIRE net for source on a constant 12v and ACC 12v on the driver side, i came up with NOTHING. To be frank, i cant believe someone hasnt had the balls to knick the wires and test them to figure it out - so, i went ahead and did that for you.. i decided to do this because the power harness for the gauge was only about 18" long at best and i wanted to mount the gauge cup right next to my A-pillar above the side window vent..

alright, now that you read my life story, lets get down to the biz.

Note: i had already tapped my vac line for the BOV, then drilled a small approx 1/4"-3/8" hole in the plastic that divides the engine bay from the clutch master cylinder compartment - ran the clear line supplied with the BOV thru that hole, and down and thru the rubber boot just beneath the master cylinder (poked a hole in it with a phillips head screwdriver and fed the tube thru that, the rubber snugs up, no worries about weather here people) i wanted the gauge signal sender inside the car, i didnt trust that cheap plastic unit against the elements or even in the bay to be honest. i zip tied the sender unit to a random harness out of the way and connected the supplied clear vac line (after heating it w/ a heat gun bc it was TIGHT). BAM-done the hard part... now to wire it up with power - the following will work to power any type of gauge or electronic 12v unit that needs to have constant power & also Acc. power that only supplies 12v when the vehicle is in Acc. mode - or turned on ...

Note 2: i chose not to use illumination as i wanted the gauge bright all the time, if you want illumination, you're probably going to have to go to the radio method.. i dont find the gauge too bright in its "bright" setting, so i skipped out on illum. and just heat shrank the wire back against the power harness cord

Step 1: Get out your favorite Torx bit / key and remove the screws that secure the kick plate, or whatever you want to call it beneath the steering wheel.. the bottom most one that encases the pedals and faces your shins. there are approx 3-4 torx screws across, and then one push pin plug you pull out on the piece that adjoins the center console plastic. i circled them in red using paint, its light, but its there..


Step 1a: Take off the side dash cover, the one you see when you open the door, by prying on it with a flat head gently (again red circle) until you can get your fingers under it, then pull evenly from the front, once it pops out it comes out all the way by opening it like a door more or less, youll see, its not hard, just be firm but gentle.


Step 2: Take your flashlight and look on the far left, you will see a few wire harnesses. you need the harness that has a bunch of tiny wires and ONE BIG RED wire in it, the big red wire is blatantly larger than the rest of the wires in the bundle.

(in the following picture, my big red wire has electrical tape on it bc i originally was going to tap that for constant 12v first, but when searching for the Acc.12v i found another wire of closer gauge to the wires supplied for the gauges power harness and chose to use that one)..

you'll see how close to the left most torx screw the harness is, and honestly, i believe it was the only bundle of wires you can pull (gently) down enough to get it in a workable position.


12v constant - Red wire w/ grey stripe

12v Acc (key in button pushed) - green wire w/ white stripe

im willing to bet the black wire in the backround was ground as well, but i extended my ground wire on the gauge harness and ran a self tapper into the side of the metal plate hidden behind the side panel when you open the door. i wanted a solid ground, and didnt want to mess with the ground in the harness. with 12v dc power - a GOOD ground is VERY important.

use a tapping method of your choice, i like to take a new razor blade, and carefully shave off the side of the insulation about 1cm, then use either the small screwdriver, or power probe to "hump" the wire up out of the insulation casing, then i take my wire im tapping, stick it thru the loop/hump i made then wrap it around the entire wire as many times as i can, flatten the two wires together and then electric tape the exposed neatly and tightly. there are a dozen methods to tap a wire, choose what you like best. they make something called t-taps, but i caution you, these wires are tiny and they didnt work for me. if you can find them in small enough gauge, guessing probably 20ga or 22ga they may work out easier for you as you dont have to cut anything, just snap em on, and then you crip a plug on your wire and that plug, plugs right into the tap you snapped on.

once the wires are tapped, an you have your ground of choice - i fed the wires up thru the side panel that we popped out in Step1a, ran them behind the metal piece, then holding the wire with two hands like your hitman and about to sneak up and fibre wire someone (lol) you can squeeze the wire between the a pillar, and the air vent, and keep pushing it around the corner. i got my wires back pretty far before i felt like it was getting too tight to keep pushing without taking more of the car apart (see pic below for finished product)







Mainly, this was for everyone searching for a way to find a constant 12v and ACC 12v on the drivers side, without having to get into the radio harness, or tap the fuse box and run wires all the way under the dash (which looks like a pain in the ass if you ask me) i sincerely hope this helps out with whatever it is you may be installing..

[Matticus91]

Cool stuff. Wish it was easier to stick a boost gauge on the N55s

[Dat1seriesdoe]

i would imagine the same power harness for tapping power would be there for the n55 as well, i dont see why it wouldnt.. and as far as tapping the boost line, you just tap into the line that runs to your diverter valve(s), or to your blow off valve, whichever you happen to have.