Test sequence

WARNING: This page is about a different car, the 2004 Audi A6, 2003 Audi A6, and 2002 Audi A6. However, it is still accessible from the selected car via links, so may be relevant.

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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NOTE: For further testing, the multimeter is attached to an ignition coil connector.

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 .