The traction control and ABS lights are continously on, cruise control doesn't work, nor any of the computer functions such as average MPG, and remaining driving range. The compass works until the car moves and then goes blank. Diagnostic code check reveals P500 (speed sensor failure). Speedo still works as does the electronic odometer. Wife took to the dealership. They indicated that they got additional codes to the P500 that the (abs?) computer was bad. I don't believe they checked any of the speed sensors. My question is are they correct or yanking my wife around trying to get her to pay the $1100 to replace a computer when it's actually a $150 sensor. Also, seems to be several speed sensors on the vehicle. One on trans, at maybe one at each wheel. I assume the one on the trans controls speedo and odometer. Are there 4 speed sensors, one at each wheel? Would the failure of one cause the symptoms described?

SOURCE: Speedo will not work with new sensor fitted

if you can try take off the dash and remove the dash unit and check to see if the speedo cable is attatched properly

SOURCE: Vitz 2005 ABS light and Speedo

as a toyota technician, its probably the wrong fitted of the ring, once you replace the bearing they will removed the ring and in that ring there is a small hole that the sensor goes in. speedometer will not work not work if there is a malfunction in abs and it is speedometer,brake warning light are integrated with abs ecu.

SOURCE: speedometer erratic/intermittent

I don't know what is causing this problem, but I know phil140701's answer is completely wrong on two counts. First, 740 Volvos starting at least in 1986 have electronic speedometers and no cable. There is an electronic sensor on the differential which sends a signal to the speedometer cluster. Second, if it were strictly mechanical with a cable then the voltage regulator could have no effect on it at all.

SOURCE: i have a 1996 4runner speedo works when it want's

ABS light is on the computer. The computer senses a fault within the system and triggers the light and shuts the system down.

SOURCE: peugeot speedo mileage counter and speedo dont

Had this problem on mine & the main dealer were stumped. Eventually found it myself after a lot of pocking about.Have a look at the wiring loom in the engine compartment. Looking under the bonnet look closely on the right hand side of the engine above the gearbox where the wiring loom passes from the rear of the engine over a metal bracket/support to the front. The loom has a tendancy to rub against the bracket and eventually damage the cables within. You will have to remove the air filter canistor & a few air hoses to get to the bracket. Good luck!