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Requirements for test:
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● → Fuse No. 232 OK (in fuse box, socket position 32)
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● Battery voltage not less than 12.7 V
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● Alternator OK
Test sequence
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‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit. Do not connect to the engine control unit itself.
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‒ Switch ignition on.
Notes:
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◆ The positive voltage supply for the engine control unit comes via contact 3 (terminal 15) and contact 62 (terminal 30).
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◆ The earth connection for the engine control unit is via contacts 1 and 2.
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‒ Connect multimeter (voltage measurement range) as follows:
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Test box V.A.G 1598/31
Socket
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Measure against
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1
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Battery positive
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2
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Battery positive
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62
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Engine earth
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‒ Specification: approx. battery voltage
- Connect multimeter (voltage measurement range) as follows:
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Test box V.A.G 1598/31
Socket
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Measure against
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3
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Engine earth
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‒ Switch ignition on.
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‒ Specification: approx. battery voltage
If the specifications are not obtained:
=> Current flow diagrams, Electrical fault finding and Fitting locations binder
Vehicles from model year 2000 onwards:
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‒ Connect multimeter (voltage measurement range) as follows:
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Test box V.A.G 1598/31
Socket
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Measure against
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121 1)
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Engine earth
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1) The Motronic current supply relay -J271 supplies terminal 121 of the engine control unit with voltage for up to 15 minutes after switching off the ignition.
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‒ Switch ignition on.
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‒ Specification: approx. battery voltage
If the specification is not attained:
=> Current flow diagrams, Electrical fault finding and Fitting locations binder
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‒ Test Motronic current supply relay -J271 => Page 28-20.
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