Originally Posted by
lionelhutz
The VSS sensor signal should be capable of driving both inputs. I'm thinking you're just seeing a ground issue between the circuits. I'd try connecting only the high side of the VSS to the DRAC. That should be pin 21 on the '0411 to pin C12 on the DRAC picture Dave posted. Both should be ppl/wht wires.
If that doesn't work, then ohmmeter the VSS wires into each module and see which ones are connected to the ground terminals.
The ppm for each signal is listed on the DRAC pictures. Speedometer is 2000ppm, cruise is 4000ppm and the RWAL is 128,000ppm. So, the speedometer would read double and the RWAL would not work if you used the VSS output on the PCM. You could fix the speedometer with a frequency divider circuit, but the RWAL would be lost.