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
VR Auto PCM Speed Sensor Info
- antus
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Re: VR Auto PCM Speed Sensor Info
Love your work, and documentation
Have you read the FAQ? For lots of information and links to significant threads see here: http://pcmhacking.net/forums/viewtopic.php?f=7&t=1396
Re: VR Auto PCM Speed Sensor Info
nice stuff!