Under dash wiring harness - LS swap


New member
Mar 17, 2021
I've put an LS5.3 into my 84 C10. the engine bay wiring is pretty time consuming, but also hard to screw up. The under dash wiring is a little bit more tricky. Namely, the black wire is supposed to go to the speedometer. but I have a cable running from the speedometer to the trans. Question 1, do I still need the black wire connected since its a mechanical speedometer and not an electric speedometer? Also, the purple and yellow wires for the brake. There's a few different places they could go on the Brake Switch. Can anyone help me with that wiring?