Makes your stepper driven idle valve work. Aftermarket, brand varies.
NOTE: UA4C vC2 and later do NOT have a stepper socket any longer, because stepper control is built into the PCB.
NOTE: Does not work with Speeduino 0.3.x.
NOTE: Some units may come with a heatsink. We do NOT recommend that you attach the heatsink. Idle valves do not draw enough current for it to be needed, and it is possible for the glue to fail and the heatsink to fall and cause a short.