Power Supply: Notes

Fig 1: Identifying Power Supply

KL30 - Battery Voltage:  It supplies the operating voltage to the ECM. Battery voltage also sustains system memory for fault codes and adaptation values.

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

Engine Control Module Relay:  It provides the operating voltage for:

• ECM 
• Fuel Pump Relay 
• Fuel Injectors 
• Oxygen Sensor Heating 
• Idle Speed Valve 
• Intake Air Resonance Changeover Valve 
• Purge Valve 
• EGS "wakeup" Call (Terminal 87a) 

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

The ECM ground pin numbers and functions are:

• Pin#
• Ground
• 06
• Fuel Injection
• 28
• Electronics and Sensor Shielding
• 34
• Remaining Output Stages (Except Ignition & Injection)
• 43
• Sensors
• 55
• Ignition
• 71
• Oxygen Sensor Signal