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HELP 2005 Kia Spectra Speedometer works intermittently

My speedometer stops working when the car warms up. I’ve taken it to be looked at but it does not “throw any codes” . I’ve looked at forums and see that this seems to be a common problem. It appears replacing sensors does not work based on the forums. One says a fix is "
THERE IS A SHORT WITHIN THE WIRING HARNESS. I had to slice the signal wire at the sensor then through the firewall and spliced in to the signal wire at the instrument cluster. IT WORKS GREAT NOW" which I don’t understand. If I tell this to a mechanic would they understand? Anyone know if any other fixes?

There is a 10A fuse for it marked ECU fed directly from ignition switch. The sensor itself looks easy to replace. As far as shorting out, you need a ohm meter to see if it’s getting grounded.

There’s a connection in the underhood junction box that splices the “in” and “out” wire from the speed sensor to the speedo and other devices. This splice goes bad over time and loses connectivity over time with the addition of heat.
The Green/Orange wire in JB4 needs to be “hot wired” to the Green/Orange wire in JB5 on the bottom of the Junction Box to solve the problem most simply.