1990 BMW 325is AutomaticFACTORY OEM SERVICE PROCEDURE

Engine Speed/Reference Point Sensor

  1. Sensor can be checked with ohmmeter or oscilloscope. Ensure ignition is off. Unplug sensor, located on front of engine near crankshaft pulley.
  2. Check resistance across 2 connector terminals (sensor side). See ENGINE SPEED/REFERENCE POINT SENSOR  table. Connect ohmmeter between each sensor terminal and engine block. Ohmmeter should not show continuity. If continuity exists, replace sensor.
  3. To check sensor with oscilloscope, unplug sensor. Connect oscilloscope leads across the 2 sensor terminals. Remove fuel pump relay to prevent engine from starting. Crank engine. Oscilloscope should show a sign wave as engine is cranked.
ENGINE SPEED/REFERENCE POINT SENSOR

Application Ohms
All Models 490-550
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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