Testing Motronic current supply relay -J271 - Vehicles from model year 2000 onwards — AUDI

APU
Special tools and workshop equipment required

V.A.G 1526 A
V.A.G 1594 A
V.A.G 1598/31

Note:

The Motronic current supply relay -J271 supplies voltage to the ignition coils with output stages and to the engine control unit (pin 121).

Test requirement:

Fuse No. 229 OK (in fuse box, socket position 29)

Test sequence

Unplug 3-pin connector from one ignition coil.
Connect multimeter (voltage measurement range) as follows:

Connector / Contact · Measure against
15 · Engine earth

Switch on ignition.
Specification: approx. battery voltage

Remove rubber seal from plenum chamber in direction of arrow-.
Remove plenum chamber cover -1- from the front.

Remove cover for electronics box in plenum chamber -arrows-.

Unplug current supply relay -3-.

Test for open circuits in the following wiring connection according to current flow diagram:

3-way relay carrier in electronics box in plenum chamber (plug-in position 3) / Contact · Connectors on ignition coils / / Contact
6 · 15

Rectify any open circuit as necessary.

If the wiring is OK:

Test supply voltage for Motronic current supply relay -J271 => Page
28-24
.
Test activation of Motronic current supply relay -J271 => Page
28-25
.

Checking voltage supply

Connect multimeter (voltage measurement range) as follows:

3-way relay carrier in electronics box in plenum chamber (plug-in position 3) / Contact · Measure against /
2 · Engine earth
9 · Engine earth

Specification: approx. battery voltage

If the specification is not attained:

Check for open circuit in wiring between central electrics unit and current supply relay.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

If no fault is detected in the wiring:

Checking activation

Connect multimeter (voltage measurement range) as follows:

3-way relay carrier in electronics box in plenum chamber (plug-in position 3) / Contact · Measure against /
4 · Battery positive

Switch on ignition.
Specification: approx. battery voltage

If the specification is not attained:

Switch off ignition.
Connect test box V.A.G 1598/31 to wiring harness for engine control unit. Do not connect to the engine control unit itself.
=> Page
24-20
.

Test for open circuit and short to positive or earth in the following wiring connections:

3-way relay carrier in electronics box in plenum chamber (plug-in position 3) / Contact · Test box V.A.G 1598/31 / Socket
4 · 21

Rectify any open/short circuit as necessary.

If no fault is found:

Fit a new Motronic current supply relay -J271.