HouseCallAuto 4/9/20101. Locate the Vehicle Speed Sensor (VSS) sensor on the top back of the automatic transmission, below the throttle body. The wire colors are Black (BLK), Orange (ORN) and Yellow (YEL). First verify that the BLK wire has a good ground.
2. Next, check the YEL wire and verify that it has battery voltage with the ignition switch on.
3. Check the ORN wire, it should have approximately 5 volts with the ignition on. If it has the correct voltage, back probe the ORN wire, and the speed sensor should pulse that voltage to ground when the vehicle is driving. On a scope, it should be a square wave signal and on a voltage meter it will read 2.5 volts while driving. If the VSS sensor does not pulse the voltage to ground and it turns, the VSS sensor is faulty.
4. If the voltage reads OK while driving the car while the speedometer is inoperative, then the speedometer is no good. Bad speedometers are fairly common on Accord.