Toyota Repair: speed sensor, vehicle speed sensor, electronic speed

Question
Ted
I have a 99 landcruiser amazon auto and the speedometer does a little dance every now and again going from 0 to 150mph in a second. this effects the gearbox and cuts out on take off if the needle is dancing. once it settles down it takes off normally. i have replaced the electronic speed sensor but this has not cured it. could it be the wiring from the sensor, there seems to be 6 wires made into 3 as it connects to the sensor. Any thoughts?

Answer
It's very possible that the speedometer itself is the problem as it receives the signals from the vehicle speed sensor and then transmits this information to the computer, an erroneous signal from the speedometer will cause the computer to react to this and can cause the problems you are describing.
This causes the ECU to be confused about the speed that it sees the vehicle to be traveling, when it sees that the speedo is falsely reporting a speed of 150mph it will turn the fuel injectors off, it's designed to do this even before reaching 150, that basically explains it without going into all of the technical mumbo jumbo.