VSS signal

[1988GTU]

Did GM follow same method of signal for the VSS from obd1 to obd2?
I am looking to find out if all that needs to be done is swapping the pigtail to go from a 3 speed auto to a 45E is just that simple... or will the ECM need to be retuned?

[Superdave]

It matters what year parts you are mixing together, most VSS's after 1992 are 24000ppm while the ones before are 4000ppm or lower.

It's an easy change in the chip.

[1988GTU]

Good info Thanks Dave!

[1988GTU]

Dave do you know what the 05 malibu with the 45e would be with one size taller tires?

[Superdave]

they won't change the VSS itself, still should be 24,000 ppm. The OBD2 ECM is probably calibrated for the factory tire size.

If it's being used on OBD1 you might be able to skew that a little to make up for tire size, the math is fairly simple.

Use the size difference results from here: http://www.miata.net/garage/tirecalc.html to calculate and adjust the PPM setting in the ECM. Should work although i've never tried it.

[1988GTU]

For some reason it's still not picking up a signal. ???