legacycentral bbs

what does the vss (speed sensor) do? i have the pulsating signal from my dash but apparently there is also a module that "should" be connected. mine isn't. my performance is good. my mileage isn't. no cels.

If I'm not mistaken the vss only goes to the tach and the trans comp... not really sure what your question is...

The VSS is in the combination meter. It sends a signal to the ECU & TCU.

Does anyone know the specifications for the older style dash mounted VSS vs the newer transmission mounted VSS? I'm guessing it's a pulse/rotation type device. Anyone know more?

when I put my svx engine in my vanagon I had to put a vss in. here is an example of one.

http://www.rockymountainwesty.com/produ ... h395ss.htm

Derek

Yeah. Got that one on my list for the conversion project. I let the stock VSS go along with the instrument cluster when I did the part out. Didn't realize that the VSS was in the dash for the 91 model year. Oh well. I've heard that these CV mounted VSS solutions are a close match to the stock Subaru VSS behavior. Just wondering how close. Seems like I need to hit the parts yard and pull one to find out.

i am very sure for the vanagon conversion the engine ecu just needs to know if you are moving or not moving to work right. for the obd1 systems.

That makes sense given the information provided in the Subaru repair manual which just states that the input to the ECU from the VSS is either 0V or 5V but does not mention any pulse accumulation per time period.

From the 1992 FSM (Section 2-7, p. 11) "The vehicle speed sensor 2 consists of a magnet rotor which is rotated by a speedometer cable and a reed switch. It is built into the combination speedometer. One rotation of the magnet rotor turns the reed switch on and off four times to produce a digital signal. The digital signal is used as a vehicle speed signal which is transmitted to the ECU."

So, does one rotation of the speedometer cable from the transmission correspond to one rotation of the final drive gear and therefore one full rotation of the tires? Or is there a geared reduction in the transmission between the final drive and the speedo?

If this motor is going in your vanagon i think you are going way too deep into this for your own good and mental sanity. The motor doesn't care how fast you are going just if you are moving or not.

Yeah, for the most part the ECU just needs to know the car is moving at some speed and isn't the same speed all the time. I've heard that the ECU may adjust how it controls the radiator fans by vehicle speed, but I don't really have any confirmation of that. So I'd try to get in the "ballpark" if you can but as long as you have some form of varying vehicle speed input to the ECU it should be happy.