VR Auto PCM Speed Sensor Info
Posted: Wed Dec 22, 2010 12:58 pm
Having finally upgraded to a digi scope, so thought it was about time to start documenting a few things. Will start with speed sensor input and output for the VR auto PCM (it also applies to series 1 and 2 VS V8 PCMs). Will also show how to convert the PCM to work with a manual hall effect signal later.
The PCM uses a chip to process the reluctor input and provide various outputs....
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...
There is a divide by 10 output that goes to pin C12. The blue trace is what gets sent to the dash...
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....
Will add more info to this thread later
The PCM uses a chip to process the reluctor input and provide various outputs....
- VSS Board Layout.jpg (487.55 KiB) Viewed 4830 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 4830 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 4830 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 4830 times
Will add more info to this thread later