Sorry if this has been discussed before but I tried searching with no success. I would like to add a couple of hidden 12V outlets under the dash and am an electrical dummy so I need detailed instructions. Where I'd really like one the most is somewhere under the drivers side dash and probably one somewhere under the passenger side dash. I currently power a handheld Garmin GPS unit, an XM Roady receiver, and a radar detector, plus the occational cell phone charger so the center console area is a bit cluttered with plugs right now. I'd like to hide them out of sight for asthetics. So.......where can I buy what I need and how do I wire it up?

Thanks in advance for any help. :thankyou2

Hey what you ought to do is just run a 14 gauge wire or so from one of the batteries on the truck, through the firewall and use that as your power source and then run a good ground wire and go to your local auto parts store and buy the female adapter for the 12v plug and mount it under your dash with the 2 wires you just ran. and if you wanted to get fancy, you could run a inline fuse with it.

I put a couple in the back of the seat mounts this way the wires are not hanging between the dash and seat, I bring them up between the seats, or things like a 12v cooler sitting on the back seat.
There is a spare fuse in the left panel of the dash marked auxpwr2, it is for a rear power jack in the suburbans, I used that until I added my second battery then powered them from it.
Ohh I added one inside the console for my cell phone

Unless you have some unusual factory options there are 3 unused circuits you can tap into inside the cab. They are available in the Relay Block I/P, also called the Mid Bussed Electrical Center (MBEC). This is the junction box under the dashboard to the left of the steering column that a trailer brake controller also plugs into.

After you remove the cover, locate connector C8, which is the upper-left position. There shouldn't be a plug in it. Pin D, the upper right pin, is hot in ACCY and RUN. It's fed through the SEO ACCY fuse, 10A, in the Left I/P fuse block. Pin A, lower left, is always hot. It's fed through the SEO B2 fuse, 30A, in the underhood fuse block. Pin E, middle right, is always hot. It is fed through the SEO B1 fuse, 15A, in the underhood fuse block, Pin F, lower right, is a ground. As far as I know, these are totally unused circuits. The other available pin in connector C8 is pin C, the upper left pin. It is hot in START and RUN, and fed by the 10A SEO IGN fuse in the underhood fuse block. This circuit also supplies power to the rear window defogger relay coil (not the defogger itself). I don't know anything about pin B. It's possibly not used.

You can use various modified connectors to hook onto these pins. The correct connector is a black 6-way Metri-Pack 280 series unsealed connector. They do not seem to be easily available. I saw a post mentioning that they were over $40 from the dealer but I haven't checked that out myself. What I did was modify the connector from a Prodigy brake controller harness to fit into the C8 position. Just be careful to not short out any pins when poking around.

If you do run a wire from the battery make sure you fuse it small enough so you limit the current to the wires rated ampacity or less. If the wire shorts to ground the resulting current will overload the wire and the result could be a fire.:eek:

I forgot to mention the mbec circuits because I have them used for other thing.

Go to radioshack either instore on via the net. If you go to the website do a search for 12VDC Car Power Accessory Outlet (http://www.radioshack.com/product/index.jsp?productId=2062272&cp=&origkw=12+volt+outlets&kw=12+volt+outlets&parentPage=search) . It is 7.49 each and already comes wired.

Go to radioshack either instore on via the net. If you go to the website do a search for 12VDC Car Power Accessory Outlet (http://www.radioshack.com/product/index.jsp?productId=2062272&cp=&origkw=12+volt+outlets&kw=12+volt+outlets&parentPage=search) . It is 7.49 each and already comes wired.


Or go to any parts store and pay $4.99 for a USA made steel mounted outlet instead of the Chinese plastic radio shack sells for twice the price.

just the first place i looked. sorry dont shoot the messenger

Sorry, Rat shack annoys me sometimes. A few years ago I got an HP CapShare scanner and it came with 1650mAH NiMH Batteries. I wanted a couple more batteries so I went to RatShack and paid $15.99 for two NiMH batteries then got home and they were 1200mAH. I went and ordered more 1650mAH batteries online for under $2 each so they ripped me off there. A few years before that when portable cd players were new I paid $300 for one for my MIL for a Christmas present. She went and bought a pair of rechargeable AA's for it and it wouldn't charge them so she took it to a RatShack store. Despite the overprices extended warranty they said they couldn't help her because I didn't buy it at that store so she went to the store I bought it from and they decided it was defective and exchanged it for their display model which was all worn and scratched. She went home and it still wouldn't charge the batteries so I went over and pulled out the user manual and drove it down to the closest ratshack store and showed them the page in the manual with the part number of the rechargeable battery and had them order it. The stupid cd player died before next Christmas and she was already so frustrated with it that she didn't even take it in under the three year warranty I bought with it. I have many many other ratshack ripoff stories so its nothing personal against you, I just have the habit now of point out any alternative to ratshack :)

Wayne,
In what manual did you find that information? Sounds like exactly what I need. My stupid Haynes doesnt identify any plugs or pins. Thanks.

Waynel;
I have 2 extra 12v plug-ins, one in the cubby hole on top of the cupholders that holds my CB radio, and another in the cubby hole in my center console that I use for my 3W cell phone (Yes there are some of us that still use analog phones because we work in remote locations to provide the reset of North America with a safe reliable source of natural gas and oil. - So G.W.B. stay below the 49th parallel!! But I sure love the ~$60 barrel of oil) Sorry about that I got on a bit of a rant. I went to Canadian Tire and got twp aux. 12v sources and a package of those quick connect wire taps and tied into the pre-existing 12v plug-ins wiring that I gained access to using a flat head screwdriver to pop out that portion of the center console. I regularly (OK 95% of the time) have my Sirius satellite radio and my radar detector plugged into the stock 12v plug-ins and have my phone and my CB into the others and I haveyet to have any problems blowing fuses in 2 1/4 years. Hope this helps.

The informatin for the midbec is at gmupfitters website. I have almost all my open spots on the midbec with a plug in now. There is a mountain of different things one can get off of it. I have various accesories and finally decided to install a secondary fuse/relay block (pictures of work in progress in garage) I plugged into the midbec for the power and ground. They are fused and not used. The best way is to modify a trailer brake plug - $7 instead of $40 at the dealer. The modify is fairly easy and it holds very well inside the midbec.

Here is the link

http://www.gmupfitter.com/publicat/2004_BB/2003_Beyond_LD_Electric_CK.pdf

look at page B-8

Winter,
Thanks, thats a treasure! Do you happen to know if the same exists for an '02? If not, they should be very close, anyway.

I found it. Thanks again.

If the 02 is the same as the 03 and up you can buy a connector for the trailer brake plug. If you spend some time looking at the end of the connector you will see that the only way to make it work is to turn it upside down and cut off the lock tab. You can also see where the safety slots are. A razor blade and a little time and they fit nice. The other thing is that you can spend $5 on just a set of crimp metrapack pins or buy the connector already with the pins and the plug. I ordered the real plugs from the dealer to look at what they have - not worth the money. The only one I haven't taken the time to replicate is the upfitter plug. I have my vss wire for the nav system there and need to make a plug for it. Thats this weekends job.

Great information! Everyone thank you so much. Now to do a little poking around and see which way I'm most comfortable with.

Newfydad, what Helms manual do you have? I bought the Helms for my '04 and it has all the stuff about the Relay Block I/P. It starts in Vol 5, Page 8-1297 with a drawing of the block labled as to what kind of connector/relay is there, then continues with other drawing of both the front and back of the block and then on into a drawing of each connector with a table of pin designation and description of the signal/power/ground on it. It does not, however tell you the detail of fusing for each wire the way the Upfitter site does.

He said Haynes manual - not Helms manual! :)

I have various accesories and finally decided to install a secondary fuse/relay block (pictures of work in progress in garage) I plugged into the midbec for the power and ground. They are fused and not used. The best way is to modify a trailer brake plug - $7 instead of $40 at the dealer. The modify is fairly easy and it holds very well inside the midbec.

You should pick up the factory aux fuse block, is uses the same metripack pins and the same style mini fuses and relays. Part number is 12160504 and it was $3.82. Its a normal part for the police package tahoe's and is behind the glove box. I wanted it more accessable so I mounted it on the drivers side.

Do they have a relay block with it also?
Might have to do some more rewireing now.
Thanks for the info.

Its spacing is such that it will hold relays also, the same ones that the truck already has. The cheapest place to get those is digikey, they are made by ohmron. Pull one on the factory ones out of your truck and you can see.
That block is listed in the upfitter guide as the radio fuse block

Where did you get the fuse panel? GM or digikey???

Its spacing is such that it will hold relays also, the same ones that the truck already has. The cheapest place to get those is digikey, they are made by ohmron. Pull one on the factory ones out of your truck and you can see.
That block is listed in the upfitter guide as the radio fuse block

The fuse panel is GM, I posted the GM p/n. I found it at www.partszoneonline.com (http://www.partszoneonline.com) they don't rip people off like gmpartsdirect by tripleing the cost of shipping.

I get the relays from digikey because they are like $4 instead or $24 from a dealer, GM buys them from ohmron or siemens or bosch so I just go closer to the source and but from an electronics distributer.
When the whole metripack system was deisgned they spaced the fuses and relays so they can use the same pins and spacing to make it easy to design fuse/relay blocks in a grid.

You can kind of see in my picture the power feed going from the top of my fuse block through the firewall to my second battery, I modified that fuse block a little bit by filing out the dividers so I can move fuses up or down one space to select which battery a load runs from.

You could just modify a plug and go off the seo fuses at the midbec. Wouldn't have to go to battery then. Fuses are already there.

Does it have a buss on the back side? Or does it have to be wired from the source to each individually?

I have other items running from the mbec power pins and this block is doing the one small fuse per load for items like my CB and such. Then I have sources coming from my secondary isolated battery there as well.

There is no bus on this its just an empty housing.

He said Haynes manual - not Helms manual! :)

Tom_S., Thanks for catching my error. So much for that speed reading class.......:p: