Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ V.A.G 1526 A
• ◆ V.A.G 1527 B
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31
• ◆ VAS 5051 with VAS 5051/1

Checking internal resistance

• ‒ → Remove engine cover -arrows-.

• ‒ → Unplug connector -arrow-.

• ‒ → Connect multimeter as follows to measure resistance:

If the specifications are not obtained:

• ‒ Replace the exhaust gas recirculation valve -N18 with exhaust gas recirculation potentiometer -G212 .

If specifications are attained:

Checking voltage supply for exhaust gas recirculation valve -N18

Test requirements:

• ● Check that power supply relay for Simos control unit -J363 is OK.

=> Simos Fuel Injection and Ignition System; Repair group 28

Note:

The power supply to the exhaust gas recirculation valve is provided by the power supply relay for the Simos control unit -J363.

• ‒ → Connect voltage tester V.A.G 1527 B as follows:

• ‒ Switch the ignition on.
• ‒ The LED should illuminate.
• ‒ Switch ignition off.

If the LED does not illuminate:

• ‒ Check the wiring from contact 1 of the connector to the power supply relay for Simos control unit -J363 (below cover on left of bulkhead) for open circuit using the current flow diagram.
• ‒ Eliminate open circuit using the current flow diagram.

If the LED illuminates:

Checking voltage supply for exhaust gas recirculation potentiometer -G212

• ‒ → Connect multimeter between contacts 2 and 4 to measure voltage.
• ‒ Switch the ignition on.
• ‒ Specification: 4.5...5.5 V
• ‒ Switch ignition off.

If specification is not attained:

• ‒ → Connect the V.A.G 1598/31 test box to wiring harness connectors; the engine control unit should not be connected. Attach the earth clip of test box to earth -arrow-.

=> Simos Fuel Injection and Ignition System; Repair group 24

• ‒ → Check for open circuit and short to positive or earth in the following wiring connections:

• ‒ Use current flow diagram to eliminate open circuit in wiring/short circuit.

If the wiring is OK:

• ‒ Replace engine control unit.

Checking signal wire between exhaust gas recirculation potentiometer -G212 and engine control unit

• ‒ → Connect the V.A.G 1598/31 test box to wiring harness connectors; the engine control unit should not be connected. Attach the earth clip of test box to earth -arrow-.

=> Simos Fuel Injection and Ignition System; Repair group 24

• ‒ → Check for open circuit and short to positive or earth in the following wiring connection:

• ‒ Use current flow diagram to eliminate open circuit in wiring/short circuit.

Checking actuation of exhaust gas recirculation valve -N18

Test requirements:

• ● Power supply OK.

• ‒ → Connect voltage tester V.A.G 1527 B to contacts 1 and 5 of the connector.
• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics". For this purpose, the ignition must be switched on.

=> Simos Fuel Injection and Ignition System; Repair group 01

→ Display on VAS 5051:

• ‒ Under -1- select the diagnostic function "03 - Final control diagnosis".
• ‒ Actuate the exhaust gas recirculation valve -N18.
• ‒ The LED must flash slowly.

Note:

Voltage testers with a low current consumption continue to glow faintly between actuation from the engine control unit (rather than extinguishing completely) and become much brighter when actuated.

• ‒ Exit function "03 - Final control diagnosis" by pressing the ◂ key.
• ‒ Press "06 - End output".
• ‒ Switch ignition off.

If LED does not flash:

• ‒ → Connect the V.A.G 1598/31 test box to wiring harness connectors; the engine control unit should not be connected. Attach the earth clip of test box to earth -arrow-.

=> Simos Fuel Injection and Ignition System; Repair group 24

• ‒ → Check for open circuit and short to positive or earth in the following wiring connection:

• ‒ Use current flow diagram to eliminate open circuit in wiring/short circuit.

If the wiring is OK:

• ‒ Replace engine control unit.