Weird speed sensor problem

[Arsine Lupin]

Recently I swapped out my HUD to an analog display in my 240sx coupe because the HUD was going out but when I swapped it out the speed would still not work and when it did it was ten miles ahead, so I went under the car and found out the speed sensor was broken almost in half and was barely being held in. So I went to the junkyard and got another speed sensor from the same car that I got the cluster from and replaced it but when it came to the wiring my car has in all honesty the worst wiring harness ever it seems like half of the factory connectors have been replaced by plain splices so I put the wires from the new sensor the same way the other ones were and miraculously it worked but here is the odd part I live in San Francisco and the speedometer only works when it is either cold outside or when the car is turned on in the morning for the first time, but once it gets warmer around noon or the car warms up the speedometer dies on me, any suggestions.

[bige240]

Ummm....are the wires all sealed up tight?? the heat from the engine or ambient temp may be causing resistance in the wire or other electrical supply and cause it to slow down current or stop the current...that's all I can think of...hope it helps