audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

Checking knock control stop > < Checking coolant temperature sender -G62
Motronic injection and ignition system (4-cyl. turbo)
Checking ignition system
Checking control unit power supply
 
G24-0020

Special tools and workshop equipment required

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

Test requirements:

  • ● Fuses for engine electronics OK

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

  • ● Battery voltage at least 12.7 V
  • ● Alternator OK

Test sequence

  • ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit .

Notes:

  • ◆ The positive voltage supply to the engine control unit is provided via contacts 3 and 121 (terminal 15) as well as contact 62 (terminal 30).
  • ◆ The earth connection to the engine control unit is provided via contact 1 and contact 2.
  • ‒ Connect multimeter as follows to measure voltage:

Test box V.A.G 1598/31
Socket

Measure to

1

Battery positive

2

Battery positive

62

Engine earth

    • ‒ Specified value: approx. battery voltage
  • Connect multimeter as follows to measure voltage:

Test box V.A.G 1598/31
Socket

Measure to

3

Engine earth

1211)

Engine earth

    1)    The power supply relay for Motronic -J271 carries voltage on terminal 121 of engine control units after switching of the ignition for up to 15 minutes.

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

If the specified values are not obtained:

  • ‒ Check the wiring connections.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

  • ‒ Check power supply relay for Motronic -J271 => Page 28-12.

Checking knock control stop > < Checking coolant temperature sender -G62