[Natalya]

Removed the 10KOhm resistor from the series, for a slightly faster pulse. This did not work. It autostopped like 1 time and that was in a stop-and-go situation where I think the car acts a little differently with the autostop function.

Maybe the pulses were still too fast then?

Or maybe there's some other problem with the signal? I have a multimeter, maybe I need to do some work to determine other characteristics of the VSS-to-ECM output. Any electrical guys know what I might try looking for? I'm thinking like voltage of the pulses or something like that.

Does the VSS pulse at all when the car is stationary? Is there a way to determine how fast the 555 timer will pulse just by knowing what resistors I used?

I have like a smorgasbord of different resistors I can try, my target is 2Hz, but I also have no way of measuring whether it's 2hz or not, I mean I can use a stopwatch but I feel like I as a human am probably not going to be accurate enough to determine if a flashing LED is in fact 2Hz by looking at it and a stopwatch at the same time.