Test sequence

• Remove cover -1- on left in engine compartment.
  Fig 1: Removing Cover 1 On Left In Engine Compartment

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• Unbolt coolant expansion tank (arrow).
  Fig 2: Removing Coolant Expansion Tank

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• Disconnect electrical wiring to Engine Coolant Level (ECL) warning switch -F66- on bottom of expansion tank.
• Lay coolant expansion tank with connected coolant hoses -1 to 3- aside.
• Remove bolts (arrows) on left cylinder head.
• Disconnect 4-pin connectors -4 to 6- on ignition coils.
  Fig 3: Removing Bolts And Ignition Coil Connectors On Left Cylinder Head

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Fig 4: Identifying Ignition Coil 4-Pin Harness Connector Terminals

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• Connect multimeter as follows to measure voltage.
  ECM POWER SUPPLY RELAY CIRCUIT TEST: VOLTAGE SUPPLY
  
  

  Connector terminal	Measure to
  1	Engine ground

• Switch ignition on.
  • Specified value: approx. battery voltage

If specified value is not obtained:

• Switch ignition off.
• Pull off rubber seal of plenum chamber cover in direction of arrow.
  Fig 5: Removing Plenum Chamber Cover

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• Remove plenum chamber cover -1- toward front.
• Remove cover for electronics box (plenum chamber) (arrows).
  Fig 6: Removing Cover For Electronics Box

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• Pry off engine control module retaining clip using a screwdriver (arrow) and move control module to side.
  Fig 7: Prying Off Engine Control Module Retaining Clip Using Screwdriver And Move Control Module

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• Disconnect power supply relay -3-.
  Fig 8: Locating Power Supply Relay

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• Check for open circuit in following wiring according to wiring diagram:
  Fig 9: Identifying Power Supply Relay Harness Connector Terminals

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  ECM POWER SUPPLY RELAY CIRCUIT TEST: OPEN CIRCUIT
  
  

  Relay carrier in electronics box, plenum chamber, position 2 terminal	Connection of ignition coils. terminal
  8	1

• Repair open circuit, if necessary.

If no wiring malfunction is detected:

• Check voltage supply of Motronic Engine Control Module (ECM) power supply relay -J171-. See CHECKING POWER SUPPLY .
• Check actuation of Motronic ECM power supply relay -J271-. See CHECKING ACTUATION .