Civic Sedan L4-1493cc 1.5L SOHC (D15B2) TBI (1989)
Speed Pulser: Description and Operation
The signal generated by the speed pulser, which produces 4 pulses (switch closures to ground) for each revolution of the speedometer cable is
used by the ECU for EVAP purge control solenoid valve, as well as automatic transmission lock-up control.