Hyundai Repair: response to speed sensor, sensor signal, speedometer

Question
From what I have seen there are 3 sensors on the tranny.  The input, output, and the one that controls the speedometer.  I replaced both input and output sensors.  On the front right wheel, all I saw was the abs speed sensor.  I inspected it and all looks good.  Are there 2 sensors on that wheel?  Makes me wonder though, the tranny looks rebuilt via the blue rtv all over.  Maybe someone put a diff tranny in?  I am tired of that speed sensor giving me issues.  thanks

Answer
The sensor you need to be looking at depends on which engine you have.

On the 4 cyl, the one that controls the speedometer also sends the signals to the computers and will cause the P0500 code.  So, if you've got a 4 cyl, you should start with the sensor that controls the speedometer.

On the 6 cyl, the right front abs speed sensor is the one that sends the signals to the computers.  So, if you've got a 6 cyl, you should start with the abs speed sensor.  But here's a diagnostic hint (for the V6 only).  If you've got ABS, and the ABS lamp comes on for self test, and the ABS lamp doesn't come on when you drive, then you can pretty much already conclude that the sensor and the wires that connect to it are okay.  In that case, you should be examining the circuit that communicates the speed sensor signal to the ECM.