Check the ecm/tcm fuse in the bcm (passanger side fuse box)fuse #25 10amps.
It the only one I can thimk of that might out right stop the car from turning over.


Im just guessing
so a little more help ,the red/white wire you tapped into ,where is it located,A-pillar,by the bcm or in the dash.

 

im going to get another car right now and i took some pics so ill stick em up when i get to a computer

 

done this before.
if you shorted the wires when you were wiring your gauges you blew a fuse.
it depends on what source you tapped, but if you tapped anything that runs off the ignition, or is on or works whenever the car key is turned into the on position it'll be the ignition fuse under the hood.
its a 20.
just replace it and make sure to ground the wire to the gauge to a good spot, and go off a fuse that can handle the power.
i recommend tapping into the windshield wiper fuse for what your doing under the dashboard.

 

this is the wire that i spliced into,its the red and white one. i already had another gauge in spliced to it but i took it out and was gonna use it again but then my car would not start so ****

 

Where is that connector located?
Need to know to figure out what that wire is for.
(When splicing in to wires Red/white is not a given they use that color to feed alot of things)
Is it on the bcm and if so where on it.

Did you use the same type of splicer as is on the green wire behind your finger in the pic. (and whats it for)
If so the wire is probably cut in half inside the insulation.(Dont use those type of splicers theey are no good)

 

Uh oh...

https://www.cobaltss.net/forums/2-0l-lsj-performance-tech-47/need-help-201905/

 

well hope all that has to happen is get the ecu flashed, i will be so happy

 

well it was my BCM, they said my battery caused it. i think it was prolly me being a dumb ****. but 700 bucks later and its back sitting in the driveway lol