There could be something holding down the output signal or a break in the connection to the ECU. If you're able to, you can send me the ECU and I'll test if it's processing the signal OK. The speed signal goes from the speedometer board to the ECU, HICAS module and transmission module. Unplug the connectors to the other two modules and then check for a signal at the ECU. The other modules or shorted wires going to them can potentially hold down the signal.