ok i tried this but when the display said PCM? I pushed the warmer button and it did nothing. I messed around with it for a bit and ended up in the part that said IPC? I said yes and when it said IPC codes I said no. IPC DATA? then came up. I scrolled through all of these options...when this came up on the display...
0 veh spd IP D 03
I drove the car with this on the display and nothing changed...the speed didnt change. I dont know if this is what you were wanting me to check. The option before this was the battery reading and it was bouncing between 13.4 & 13.5 so I would think the speed would have also changed if it was getting a reading.

 

Yeah...same info, just a different location.
So now we KNOW the PCM is not getting a speed signal. Even tho you were reading the ICP data, the speed sensor data comes from the PCM to the ICP. If the trans was shifting, but the speedo wasn't working, then you may have an ICP issue, but this is definitely a speed sensor problem. My bet is it is the wiring. Unfortunately, it does take time to test everything. The next step, if I were fighting this one, would be to check the speed signal AT the PCM connector, and OHM the wires from the PCM to the sensor connector. I'm betting one(or both) will show an open, or a short.
You can also test the sensor right at the sensor itself with a multimeter that is capable of reading A/C voltage.

 

Greetings I just ran into a similar problem on my 99 deville, It start not pull past 25 to 30 mph...I checked the fluid level and saw that it was low and added fluid...eventually the car wouldn't change gears...Pulled the code and I got the Speed Sensor no signal code...I'm probably going to it taken to a Transmission Shop on Monday to get a diagnosis and estimate...prayerfully its something that can be fixed thats not to expensive...I will mos def keep you posted since we're in the same boat. I'm actually encourage to hear that the speed sensor can be causing it...

 

hey,
As you said that you are having this kind of problems in your car , exactly same problems i'm also facing with my car i looking for a best car mechanic in near by Duncanville , so anyone knows about it then plz inform me or PM me.