Where to tie in on a good electrical point (underdash) for newer Corvette/GM Product?

[Larry E.]

Try to make a long story short. Will be adding a GPS system that needs 12 Volts to
go on when engine runs;off when engine shuts off. GPS system will augment my OnStar.
My application is a 2014 Silverado. All GM's are somewhat similiar so if one where
to do this to a newer Corvette where is a good "tie in point" to get 12 Volts? Not constant. We all
know in the older GM's this was simple by connecting to the fuse panel. Any ideas will
be appreciated. Thanks in advance--Larry

[Paul D.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

I'm sure others with more experience than I will chime in, but on today's vehicles, I would discourage connecting anywhere other than at the fuse/relay/power connection box out under the hood. I think there is a switched connection out there, but not sure.

[Richard M.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

You may be able to find wiring diagrams for your vehicle online. However, cumbersome and complex for simple tasks.

I've done several Auto Command Remote Start installations on the newer cars. The wiring to the module requires tapping into several IGN points. Many vehicles have IGN1, IGN 2, IGN 3 , etc connection points. They tie to various items when IGN on via separate circuits and relays. Their website, http://www.readyremote.com/ used to have wiring info for all vehicles but is now locked and requires a code to access it using the purchasers' product codes.

Here is a website they provide now which may lead you to some info and vehicle specific "component locator" documents and wiring connection info. I haven't inquired there but it may help. It's vehicle specific. https://www.directechs.com/default.aspx

Rich

[Larry E.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

Between my owners manual (2014 Silverado) and the internet I have found the proper fuse
in the front side panel fuse box. (By drivers door) I will use CarQuest#ST231 fuse taps to tie
into the fuse. Hope it works. Thanks for the responses. Larry

[Mike H.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

Larry
I hope you haven't tackled this yet. You do not want to access any Ignition or Accessory power inside the cab of the vehicle. The GM data system used in the 2007+ trucks does not allow for excessive current draw and is very sensitive, basically the "ignition or accessory" side of the vehicle that you are used to seeing behind the key cylinder is all low current and data signal - there is not a true "ignition" circuit in the car, as even the radio is turned on using binary code. I spent 15years doing custom auto security and have seen many awful things from people trying to locate 12v in modern GM stuff. The safest point is the large fusebox under the hood, utilizing a SPDT 5 pole relay. I can't remember exactly what fuse, but you need a fuse that is true ignition (12v+ during acc, ign and start) otherwise the GPS will power up momentarily until you get to crank, power down, and power back up when you return to ign run. Identify a fuse that isn't ABS ECM or SIR, unplug the fuse and turn igntion on, you want to grab the input leg of the fuse (the powered side when the fuse is removed). Run this wire to a 2 or 5A fuse, then to pin 86 of the relay. Pin 85 goes to ground, pin 87 goes to a the battery terminal on the fusebox (run a fuse in line here in accordance with the fuse in the GPS). Pin 30 ends up the output to the cabin, there are several ground points throughout the dash reinforcements. You can pull the LH fusebox cover off the dash and tuck the wire around the a pillar and dash too. The main harness around the parking brake has an enormous grommet that you can slice to poke through, just know that on the interior there is a rubber donut that fills the grommet, pull that out and once the wire is through the firewall reinstall it. The relay is available at Best Buy, Radio shack, or any audio / security store for under $10.

[Larry E.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

Larry
I hope you haven't tackled this yet. You do not want to access any Ignition or Accessory power inside the cab of the vehicle. The GM data system used in the 2007+ trucks does not allow for excessive current draw and is very sensitive, basically the "ignition or accessory" side of the vehicle that you are used to seeing behind the key cylinder is all low current and data signal - there is not a true "ignition" circuit in the car, as even the radio is turned on using binary code. I spent 15years doing custom auto security and have seen many awful things from people trying to locate 12v in modern GM stuff. The safest point is the large fusebox under the hood, utilizing a SPDT 5 pole relay. I can't remember exactly what fuse, but you need a fuse that is true ignition (12v+ during acc, ign and start) otherwise the GPS will power up momentarily until you get to crank, power down, and power back up when you return to ign run. Identify a fuse that isn't ABS ECM or SIR, unplug the fuse and turn igntion on, you want to grab the input leg of the fuse (the powered side when the fuse is removed). Run this wire to a 2 or 5A fuse, then to pin 86 of the relay. Pin 85 goes to ground, pin 87 goes to a the battery terminal on the fusebox (run a fuse in line here in accordance with the fuse in the GPS). Pin 30 ends up the output to the cabin, there are several ground points throughout the dash reinforcements. You can pull the LH fusebox cover off the dash and tuck the wire around the a pillar and dash too. The main harness around the parking brake has an enormous grommet that you can slice to poke through, just know that on the interior there is a rubber donut that fills the grommet, pull that out and once the wire is through the firewall reinstall it. The relay is available at Best Buy, Radio shack, or any audio / security store for under $10.

Thanks Mike>These new Vehicles make you pull your hair out sometimes. Thanks for the info. Will have to go to
plan B. Will use the R.A.P.(Turns on/off with engine run) inside the center console. Will have to figure how I can run the wire underneath the rug
to the dash. I could use the A/P in the ash try area but it stays on all the time. Thanks again. Larry
P.S. Any ideas will be very appreciated.
Thanks Mike>

[Larry E.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

Larry
I hope you haven't tackled this yet. You do not want to access any Ignition or Accessory power inside the cab of the vehicle. The GM data system used in the 2007+ trucks does not allow for excessive current draw and is very sensitive, basically the "ignition or accessory" side of the vehicle that you are used to seeing behind the key cylinder is all low current and data signal - there is not a true "ignition" circuit in the car, as even the radio is turned on using binary code. I spent 15years doing custom auto security and have seen many awful things from people trying to locate 12v in modern GM stuff. The safest point is the large fusebox under the hood, utilizing a SPDT 5 pole relay. I can't remember exactly what fuse, but you need a fuse that is true ignition (12v+ during acc, ign and start) otherwise the GPS will power up momentarily until you get to crank, power down, and power back up when you return to ign run. Identify a fuse that isn't ABS ECM or SIR, unplug the fuse and turn igntion on, you want to grab the input leg of the fuse (the powered side when the fuse is removed). Run this wire to a 2 or 5A fuse, then to pin 86 of the relay. Pin 85 goes to ground, pin 87 goes to a the battery terminal on the fusebox (run a fuse in line here in accordance with the fuse in the GPS). Pin 30 ends up the output to the cabin, there are several ground points throughout the dash reinforcements. You can pull the LH fusebox cover off the dash and tuck the wire around the a pillar and dash too. The main harness around the parking brake has an enormous grommet that you can slice to poke through, just know that on the interior there is a rubber donut that fills the grommet, pull that out and once the wire is through the firewall reinstall it. The relay is available at Best Buy, Radio shack, or any audio / security store for under $10.

Question for Mike>Do you see any problem if I splice into the Accessory Port wires? I don't want to run the big
connector that plugs into it. BTW-Is it still a no-no to tap into the Fuse that supplies power to this particular
accessory port??? Can't understand the difference of getting the 12V from either source since it is the same?? Thanks-Larry

[Mike H.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

The only absolutely risk free way that I know of to source an additional 12v ignition is the way that I outlined. This way I know that the vehicle electronics are completely safe, and that my additions are very safe. There may be other ways but I don't risk it. I did this for a Garmin in both my 10 and 13 Silverados. I'm a little confused on your statement about the big connector that plugs into it. Do you mean the male cigarette lighter end on the Garmin cable? If so I am almost positive that end takes the 12v in the aux socket and drops it to a 5vdc micro usb configuration.

[Larry E.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

The only absolutely risk free way that I know of to source an additional 12v ignition is the way that I outlined. This way I know that the vehicle electronics are completely safe, and that my additions are very safe. There may be other ways but I don't risk it. I did this for a Garmin in both my 10 and 13 Silverados. I'm a little confused on your statement about the big connector that plugs into it. Do you mean the male cigarette lighter end on the Garmin cable? If so I am almost positive that end takes the 12v in the aux socket and drops it to a 5vdc micro usb configuration.

Mike: Yes that is what I ment; I don't want to use it if at all possible. I also have Garmin Power Cable
#010-11131-10 which also drops the volts down to 5 VDC. One end has the micro usb and the other
end has 2 bare wires in which I want to tap into something safe. I have found the fuse in front panel that
services the Access. Power Port by the ash try. Question: Can I use a fuse tap to make contact with that
fuse to give me the positive? If no can I splice into the Access. Power Port. (Which is the same electrical point)?? What differenct
would it make on weather I get 12 volts from the APP or the Fuse that services it??. Larry

[Larry E.]

Re: Where to tie in on a good electrical point (underdash) for newer Corvette/GM Prod

OK; completed the project fine. Had to do a lot of research and watch youtube. Anyway found a RAP spare spade
in the 2014 Silverado fuse box. I would suspect this hookup is available in all GM vehicles but not sure. It gives the option
of changing your outlet plugs from RAP to Plug being on all the time by moving the big 50 AMP fuse.(#10&#11 Position) Picture is below and
shows this fuse box. I also would take heed from Mike's statement above. Unless you are sure; to do not attempt this with
your model. Thanks again--Larry