Anyone pulled their power steering fuse?

[CTScott]

Originally Posted by CrankyOldMan

I've located some potential parts for these, but I'm not sure how I'd go about measuring the pulse per mph. Do you by chance already know what it is?

I'm also guessing that the signal is 12V, so you'd have to use a regulator or voltage divider to get down to the 5V input that the F/V chip is expecting. I'm still looking through the datasheet to see exactly how the F/V converter works. Any suggestions on what kind of comparator would be the right type to use?

The VSS signal is actually a 5V signal. If memory serves me correct the frequency is 100 Hz at 40 MPH and about 20 Hz at 10 MPH.

For the comparator, a general purpose one, like the LT1011 would be fine. It is amazing how much more complicated this gets trying to do it with analog, rather than digital. I should just build you up one to experiment with using a microcontroller. I could make a simple little black box that connects to ignition switched power and then has an output to drive the relay coil. I could have a pot on the box to adjust the switch over speed.