Quote:
Originally Posted by Natalya
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2: When the switch is set to the right, everything works normally, car drives along reading the correct speed. When the switch is set to the left it is SUPPOSED to get a signal from the 555 timer of a square wave and the VSS is cut out of the equation.
Apparently that's not the case.
Observed behaviour when I press the switch to the left is that the car's speedometer still works normally, but auto-stop will never happen. I think the ECM is somehow getting a combined signal at the wrong voltage or something from the VSS and the 555 timer and to play it safe it won't auto stop. I'm absolutely baffled as to how the VSS signal is going through an open switch into the ECM. Does anyone have any ideas what might be going on here?
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Natalya,
Great project. Here's what I think about the speedometer issue:
I think you've connected to the wrong pin/wire at the speedometer, or maybe at your switch.
Possibly your switch has quite a few terminals on it (based on my recent experience buying switches for my fuel injector cutoff) - and just maybe you've got the RIGHT wires at the speedo sensor, but didn't connect to the right ones on the switch. I suspect you're using a SPDT or maybe a DPDT. Either way, I found the pins needed were NOT where I expected them to be. Test the function of the different pin combinations with a multitester or similar.
Speedometer: I expect there are three pins at the speedometer. I wired my MPGuino mpg calculator to my '97 Civic. It needed a speedometer connection, so I had to learn what was what. At home, I might still have my color coding notes for the speedo sensor. I would not be surprised if the Insight sensor has the same coding. Honda seems to like to keep their color coding the same. I think some people wired theirs at the computer, but I connected mine at the speedometer sensor on the transmission.
Anyway, my recollection is there are three speedometer pins. One is +, maybe only 5 or 10V instead of 12V. I think one is ground and the third one is the output signal, which is the one you need to fake. I expect the output goes to the computer, not to the speedometer. I expect the speedometer is provided a signal from the computer.