Motronic Engine Control Module (ECM) power supply relay -J271-, checking: Notes

WARNING: This page is about a different car, the 2006 Audi A4, 2005 Audi A4, 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Special Tools - Motronic Engine Control Module (ECM) Power Supply Relay -J271-, Checking

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Special tools and equipment

VAG1526 A
VAG1594 A
VAG1598/31

NOTE: The Motronic engine control module (ECM) power supply relay -J271- supplies the ignition coils with output stages as well as the engine control module on Pin 121 with power.

Test sequence

Fig 2: Removing Cover In Engine Compartment (Left Side)

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Disconnect cover -1- on left in engine compartment.

Fig 3: Removing Coolant Hoses

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Unbolt coolant expansion tank (arrow).
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.

Fig 4: Removing Bolts On Left Cylinder Head & Disconnecting 4-Pin Connectors On Ignition Coils

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Remove bolts (arrows) on left cylinder head.
Disconnect 4-pin connectors -4- to -6- on ignition coils.

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

Fig 5: Identifying Connector Terminals 1 And 4

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Connect multimeter as follows to measure voltage.

Connector Terminal	Measure to
1	Engine ground

Switch ignition on.

Specified value: approx. battery voltage

If specified value is not attained:

Switch ignition off.
Pull off rubber seal of plenum chamber cover.

Fig 6: Identifying Plenum Chamber Cover & Removing Rubber Seal

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Remove plenum chamber cover -1- toward front (arrows).

Fig 7: Removing Securing Clips And Cowl

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Pry off both trim caps -3- with a screwdriver.
Undo hex nuts -4- a few turns.
Release wiper arms -2- from pivot shaft by tilting them slightly.
Remove hex nuts completely and remove wiper arms.

Disconnect retaining clips -1- and remove air cowl grille -5-.

Fig 8: Removing Screws And Cover From E-Box In Plenum Chamber

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Remove cover for electronics box (plenum chamber) (arrows).

Fig 9: Using Screwdriver To Remove Retainer Bar And Engine Control Module (ECM) J623

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Lift off engine control module retaining clip using a screwdriver (arrow) and move control module to side.
If installed, unclip transmission control module retaining clip and place control module on one side.

Fig 10: Removing Motronic Engine Control Module (ECM) Power Supply Relay J271 From E-Box

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Disconnect power supply relay -2-.

Fig 11: Identifying Secondary Air Pump Relay Terminals

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Check for open circuit in following wiring according to wiring diagram:

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 -J271-. Refer to Checking power supply .
Check actuation of Motronic Engine Control Module (ECM) power supply relay -J271-. Refer to Checking actuation .