Rallye cluster gauge issues - 67 Barracuda

I would think a tachs backlight would be connected to the orange wire/illumination circuit somewhere. Tach is accessory. These harnesses didn't include provisions for accessories. Thats why the factory tach package included a add on harness for it. I dont know how you or a previous owner are going about tapping wires or how you lost power to the limiter. Twist them together and tape them up doesn't always work. Could be a loose pin at circuit board too. Moving the wires about would move that pin. The only wires that depend on the pins are those to light bulbs. Every other wire could be attached directly on the corresponding post with a ring terminal, same as the wires on the amp gauge. Toothed washer and 10-32 hex nut on top of the speedy/PAL nut. E-body for example doesn't have a printed circuit board. all the wires are attached with 90 degree push on like the one on your noise cap'. Those owners have to know which color wire goes where.