There is a repair part available to fix the outside temp sensors that use the separate temp guage, mostly 80s and 90s. It comes with a long lead, maybe ten feet in length, and can be spliced into the original lead at any place that its convenient. The system works by reading the resistance of the sensor tip. It doesn't care about the length of the wire. Later vehicles use a plug in sensor that provides an input that is shared to multiple systems.