BMW 318/325/M3/525/535/M5 1989-1993 Repair Information

Testing

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IGNITION COIL



Except M42 and M50 Engines
  1. With the ignition OFF, disconnect the ignition lead from the coil tower. Disconnect the primary wires from the screw terminals on the coil. Note that the terminals are marked with a 1 and 15. The center tower terminal is called 4.
  2.  
  3. Use an ohmmeter and check the resistance between the 2 screw terminals, 1 and 15. The resistance should be 0.45-0.55 ohms.
  4.  
  5. Use an ohmmeter and check the resistance between the terminals, 4 and 15. The resistance should be 5400-6600 ohms.
  6.  
  7. Replace the coil if not in specification.
  8.  

M42 and M50 Engines

See Figures 1, 2 and 3



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Fig. Fig. 1: Removing the coil pack cover-M42 engine



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Fig. Fig. 2: Coil pack cylinder assignments-M42 engine



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Fig. Fig. 3: Terminal numbering-M42 and M50 engines

  1. On the M50 engine, remove the valve cover cladding as done when removing spark plugs. On the M42 engine, pull off the coil pack cover.
  2.  
  3. With the ignition OFF, disconnect the harness connector by releasing the locking bar and pulling off the connector.
  4.  
  5. Check the resistance between the outside terminals of the the 3 terminals in the coil connector socket. They are terminals 1 and 15.
  6.  
  7. The resistance should be 0.4-0.8 ohms. Replace the coil if out of specification. The secondary side of the coil cannot be checked due to the design of the coil.
  8.  

 
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