2002 BMW M3 2D ConvertibleFACTORY OEM SERVICE PROCEDURE

Power Supply: Notes

Fig 1: Identifying MS S54 ECM Power Supply
G03394639Courtesy of BMW OF NORTH AMERICA, INC.

KL30 - Battery Voltage:  B+ is the main supply of operating voltage to the ECM.

Power Supplies:  The power supplies (KL15 and ECM Relay) are fused to the MS S54 ECM. The fuses are housed in the Engine Fuse Block located in the Electronics Box.

KL15 - Ignition Switch:  When the ignition is switched "on" the ECM is informed that the engine is about to be started. KL15 (fused) supplies voltage to the Engine Control Module Relay and the Fuel Injector Relay. Switching KL15 "off" removes the ECM operating voltage.

Fig 2: Identifying Power Supplies (Kl15 And ECM Relay)
G03394640Courtesy of BMW OF NORTH AMERICA, INC.

Engine Control Module Relay:  The ECM Relay provides the operating voltage for:

  1. ECM 
  2. Fuel Injector Relay 
  3. Idle Air Actuator 
  4. Evaporative Emission Valve 
  5. Fuel Pump Relay 
  6. Ignition Coils 
  7. DMTL 
  8. Camshaft Sensor 
  9. Hot Film Air Mass 
  10. Oxygen Sensor Heaters 

Ground:  Multiple ground paths are necessary to complete current flow through the ECM.

The ECM ground pin numbers are:

  1. Connector X60001 
  2. Connector X60004 
  3. Connector X60005 
  4. Pin 4 - Ground for ECM 
  5. Pin 5 - Ground for ECM 
  6. Pin 5 - Ground for ECM 
  7. Pin 5 - Ground for ECM 
  8. Pin 6 - Ground for ECM 
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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