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Thanks for posting
The diagnosis for the speed sensor is correct for this code, I assume you replaced the one in the transmission but there is another speed sensor built into the speedometer which sends speed information to the computer, since the speedo is not working the computer sees no information from it and turns the light on. The transmission sensor sends speed signals to the speedometer first then to the computer, the sensor in the speedometer is not replaceable seperately so the speedo assembly needs to be replaced, not the whole cluster, just the speedometer part.
To replace the speedo assembly the gauge cluster has to be removed and opened up from the back to get the speedo out. The code is set when the computer fails to see a speed input signal, although the transmission speed sensor is the most common part to fail it is possible that the speedometer sensor is the cause since it receives the signal from the transmission sensor, the transmission sensor sends an analog waveform to the speedo sensor which converts this into a square wave that the computer can read. The only other problem I have seen cause this is a stripped gear on the transmission sensor drive gear inside the transmission which is very uncommon. Once the speed sensor code is fixed the other lights will go off, when there is an input signal malfunction to the computer (ECM) the other systems like abs and traction control become disabled, this is so by design.