why doesnt vtec work if my speedometer cable is unplugged? I am just curious because in my cable tranny the cabel is all mechanical and not electric at all so how does the ecu know if it is plugged in or not? just wondering....

 

VTEC activation requires the VSS to be working. The cable from the tranny goes to the gauge cluster, which houses the speed sensor.

 

car must show speed greater than 26 MPH or something before vtec engages

 

so basically the speedo is how vtec knows that you are actually going rathetr than just reving it up in neutral?

 

yes

 

the car has to be over 20 mph for the vtec to hit plug it in and it will work

 

Here is a pic of the speed sensor and where it connects: