Code P1506: Idle Air Control System Circuit Malfunction
WARNING: This page is about a different car, the 1995 Mazda B4000, 1995 Mazda B3000, and 1995 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Trouble Code No. P1506 Idle Air Control System Circuit Malfunction
Fig 2: Trouble Code No. P1506 Idle Air Control (IAC) Solenoid Circuit Diagram