1996 Cadillac SLS

Transmission problem
1996 Cadillac SLS V8 Front Wheel Drive Automatic 127000 miles

The oil-leaking engine runs fine, but surges when driven (I don't recall at what speed that begins). I checked for trouble codes and a " P0503 Speed Sensor A" shows up. Is " Speed Sensor A" the one on the passenger side? I have replaced the speed sensor at the passenger-side trans output. It is possible the wiring to that is faulty, but I found it easier to replace the sensor, than mess with the wiring; however, that didn't solve the problem. Can I check the plug for the sensor, to tell whether it is receiving proper input?
October 19, 2009.

Yes. Here is what you need to do: raise and safely support the vehicle
disconnect the VSS wire connector
connect an ohmmeter between the terminals
most sensors usually between 190-250
place the vehicle in drive and allow the wheels to rotate.
The ohmmeter should fluctuate, if it does not or if it not within that specification, replace the sensor.

Oct 19, 2009.
You could check the terminal tension of the connector, with a terminal of the corresponding type(metri-pak 150 male). The speed sensor is a signal generator, the only way to check the circuits would be to measure them individually, from the sensor connector to the ECM connector. Is the code shown to be history, or current, and if cleared does it reset? Also, does the speedometer seem to function properly?

Oct 20, 2009.