The PCM uses a chip to process the reluctor input and provide various outputs....
- VSS Board Layout.jpg (487.55 KiB) Viewed 5429 times
The signal from the reluctor speed sensor (yellow trace) is clamped to ~1.4v p-p (blue trace) before the input of the VSS processing chip. I have used a sine wave for this test as it was just done on the bench...
- Input to VSS Processing Chip.jpg (36.22 KiB) Viewed 5429 times
There is a divide by 10 output that goes to pin C12. The blue trace is what gets sent to the dash...
- PCM to Dash.jpg (39.25 KiB) Viewed 5429 times
The CPU uses a counter for calculating the vehicle speed. A 3uS pulse from the VSS processing chip (blue trace) occurs on every rising and falling edge of the reluctor signal....
- Output to VSS Counter.jpg (33.87 KiB) Viewed 5429 times
Will add more info to this thread later
