'87 Volvo 740 2.3 Turbo MAF  Bosch p/n 0 280 212 007  (black plastic case)

Pin #1  Ground (MAF signal - local)
Pin #2  Ground for filament burn-off and CO idle adjustment (at PCM)
Pin #3  MAF output (~1 - 5v)
Pin #4  Filament burn-off (4v for 1 second after shut-down, controlled by PCM)
Pin #5  12v Power input
Pin #6  CO Idle adjustment