[targa80]

There is a male/female connector that provides the pass through of the red/black wire from the ignition switch drivers side foot well through the frame into the frunk on the drivers side. To access those chassis mounted female connectors may require removing some of the vent duct work in the frunk. first isolate which connector it is on the underside of the drivers foot well. Then you can assess how much you need to remove in the drivers side frunk to access the mating connector. The connectors are molded rubber so you are not going to be able to replace it completely. I would start by unwrapping the insulation on the tach wire from either the ignition switch or the tach itself. If your lucky it is not fully burnt and follow it back to where the insulation is still sound. You can then splice in a new wire from that point.