The magnetic type of position sensor is simply a magnet with a coil of wire wrapped around it. The clearance between the pickup and reluctor is critical. Be sure to check it. Specs are usually between 0.030" and 0.070" (0.8 mm to 1.8 mm).

Fig 15 - Checking For Pulses from Magnetic Distributor Pickup Disconnect the distributor from the ignition module. Connect the DMM across the pickup and set it to AC volts. When the engine is cranked, pulses should appear on the bar graph. If no pulses appear, it is likely the reluctor wheel or the magnetic pickup is faulty. Use this technique for other magnetic position sensors too. On GM cars, remove the distributor cap for access.