Hello Scozzy,
LS400/Celsior speedo will often simply stick on the 0km/h peg...sharp tap to the instrument binnacle will dislodge. I have replaced the fuel pump and sender unit in my 1995 LS400... It's important to check that the appropriate pin on the ECU is getting correct voltage. You can simply google to find which pin and which colour wire is the appropriate connector. Use carbon grease on the connectors in the fuel tank to ensure proper connection.If you have the instrument binnacle removed you can meter incoming voltage at the gauge itself. The same can be done with the speedo but VSS sends voltages will vary with speed, naturally. Good luck!
I continually scan this forum
MAC WORRAPS
Sydney and Wollombi (Hunter Valley)