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Idle/Throttle Speed Control Unit: Testing and Inspection



THROTTLE VALVE CONTROL MODULE, CHECKING

NOTE: If the throttle valve control module -J338- is removed and installed or replaced, "Basic Setting, Initiating (Function 04)" must be initiated for matching of system components. Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection

Special Tools, Testers And Auxiliary Items
- VAG 1551/1552 scan tool with VAG 1551/3 adapter cable
- VAG 1598/18 test box
- Multimeter (Fluke 83 or equivalent)
- Connector test kit VW 1594
- Wiring diagram

Checking Voltage Supply





- Separate 8-pin connector to throttle valve control module -J338-.
- Connect multimeter using test leads from VW 1594 to measure voltage at terminals 3 and 7 of connector.
- Switch ignition on.

Specification: 9.0-14.5 volts

- Connect multimeter using adapter cables from VW 1594 to measure voltage at terminals 4 and 7 of connector.

Specification: 4.0-6.0 volts

- Switch ignition off.

If the specifications are not attained:





- Connect VAG 1598/18 test box to ECM wiring harness.





- Check wiring between test box and 8-pin connector for open circuit according to wiring diagram.
- Terminal 3 and test box socket 10
- Terminal 4 and test box socket 41
- Terminal 7 and test box socket 33

Resistance: maximum 1.5 Ohms

- Check wiring at 8-pin connector for short circuit to each other.
- Terminal 7 and test box socket 10
- Terminal 7 and test box socket 41
- Terminal 4 and test box socket 33

Specification: Infinity Ohms

- Reconnect connector.

If no wiring malfunction is detected:
- Replace Engine Control Module (ECM) -J220-.
- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group See "Readiness Code, Creating". Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection

Checking Closed Throttle Position (CTP) switch
- Engine running at idle

- Connect VAG 1551/1552 scan tool and select "Engine Electronics" address word 01 See "On-Board Diagnostics II With VAG 1551". Testing and Inspection

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08 and press -Q- button to confirm input.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press buttons -0-, -0- and -5- for display group 005 and press -Q- button to confirm input.

Indicated on display (1-4 = Display fields)

Read Measuring Value Block 5 ->
1 2 3 4

- Check closed throttle position switch (display field 4).





- Switch ignition off.





- Connect VAG 1598/18 test box to ECM wiring harness.
- With throttle valve closed connect multimeter to measure resistance at test box sockets 10 and 33.

Specification: maximum 5.0 Ohms

- Slowly open throttle.

Specification: Infinity Ohms

If the specifications are not attained:





- Separate 8-pin connector to throttle valve control module -J338-.
- Check wiring between test box and 8-pin connector for open circuit according to wiring diagram.
- Terminal 3 and test box socket 10
- Terminal 7 and test box socket 33

Resistance: maximum 1.5 Ohms

- Check wiring at 8-pin connector for short circuit between terminal 7 and test box socket 10.

Specification: Infinity Ohms

- Reconnect connector.

If no wiring malfunction is detected:
- Replace throttle valve control module -J338-.
- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group See "Readiness Code, Creating". Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection

Checking Throttle Position (TP) Actuator And Throttle Position Sensor

Test Conditions
- Coolant temperature at least 80 °C (176 °F)

Test Sequence
- Engine running at idle

- Connect VAG 1551/1552 scan tool and select "Engine Electronics" address word 01 See "On-Board Diagnostics II With VAG 1551". Testing and Inspection

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08 and press -Q- button to confirm input.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press buttons -0-, -3- and -7- for display group 037 and press -Q- button to confirm input.

Indicated on display (1-4 = Display fields)

Read Measuring Value Block 37 ->
1 2 3 4

- Check the specifications for the idle control (display field 1-4).





- Press -C- button.
- Press buttons -0-, -3- and -6- for display group number 036 and press -Q- button to confirm input.

Indicated on display (1-4 = Display fields)

Read Measuring Value Block 36 ->
1 2 3 4

- Check the specifications for the idle control (display field 2 and 3).





Evaluating Display Group 037:





Evaluating Display Group 036:





Continuation

- Switch ignition off.





- Connect VAG 1598/18 test box to ECM wiring harness.
- Switch ignition on.
- With throttle closed connect multimeter to measure resistance at test box sockets 27 and 53.

Specification: 3-200 Ohms

If the specification is not attained:





- Disconnect 8-pin connector from throttle valve control module -J338-.
- Repeat resistance measurements of throttle valve control module at terminals 1 + 2

Specification: 3-200 Ohms

If the specification is not attained:
- Replace throttle valve control module -J338-.

If the specification is attained:
- Check wiring between test box and 8-pin connector for open circuit according to wiring diagram.
- Terminal 1 and test box socket 27
- Terminal 2 and test box socket 53
- Terminal 7 and test box socket 33
- Terminal 8 and test box socket 62

Resistance: maximum 1.5 Ohms

- Check wiring at 8-pin connector for short circuit to each other according to wiring diagram.
- Terminal 1 and test box socket 53
- Terminal 1 and test box socket 62
- Terminal 1 and test box socket 33
- Terminal 2 and test box socket 33
- Terminal 2 and test box socket 62
- Terminal 7 and test box socket 62

Specification: Infinity Ohms

- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group See Readiness code, creating. Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection

Checking Throttle Position (TP) sensor
- Connect VAG 1551/1552 scan tool and select "Engine Electronics" address word 01. When doing this the ignition must be switched on but engine not running. Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08 and press -Q- button to confirm input.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press buttons -0-, -0- and -3- for display group 003 and press -Q- button to confirm input.

Indicated on display (1-4 = Display fields)

Read Measuring Value Block 3 ->
1 2 3 4

- Check the TP sensor specification (display field 3).





- Slowly open throttle valve and watch angle display in display field 3.

- The value must increase uniformly over the complete range.

- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.

NOTE: The displayed value is dependent on the tolerances of the Throttle Position (TP) sensor and does not correspond to the actual opening angle. The maximum permissible displayed value is 90.0 <°.

If the value does not increase uniformly:
- Replace throttle valve control module -J338-.
- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group See Readiness code, creating. Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection

Evaluating Display Group 003:





Check Wiring





- Connect VAG 1598/18 test box to ECM wiring harness.
- Connect multimeter using test leads from VW 1594 to measure resistance at test box sockets 01 and 40 and check wiring for short circuit to Ground (GND).

Specification: Infinity Ohms

- Set multimeter to voltage measurement range.
- Switch ignition on.
- Check wiring for short circuit to positive (B+). If necessary, note voltage value.
- Switch ignition off.





- Separate 8-pin connector to throttle valve control module -J338-.

Continuation if voltage is present:

If voltage of about 5 volts was present:
- Connect multimeter using test leads from VW 1594 to measure resistance at test box sockets 40 and 41 and check for short circuits to each other.

Specification: Infinity Ohms

If the voltage was approx. battery voltage:
- Check wiring at 8-pin connector terminal 5 for short circuit to battery positive (B+) according to wiring diagram.

Continuation if no voltage is present:
- Check wiring between test box and 8-pin connector for open circuit according to wiring diagram.

Terminal 5 and test box socket 40

Resistance: maximum 1.5 Ohms

If no wiring malfunction is detected:
- Replace throttle valve control module -J338-.
- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group See Readiness code, creating. Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection



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