Throttle Valve Control Module J338, Checking

Throttle Valve Control Module, Checking

Components of throttle valve control module (J338): Throttle valve drive (G186), angle sender 1 for throttle valve drive (G187) and angle sender 2 for throttle valve drive (G188).


NOTE: If the throttle valve control module is replaced, the new control part must without fail be adapted to the engine control module.
Refer to "Throttle Valve Control Module, Adapting to Engine Control Module" Service and Repair


On vehicles fitted with an automatic transmission the transmission control module must also be adapted:

Special tools and equipment
- Scan tool VAG 1551 or vehicle system tester VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/31
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Test conditions
- Throttle valve not damaged or dirty.
- Coolant temperature must be at least 80 °C, See display group 04, display zone 3.

Test sequence
- Connect the scan tool VAG 1551 (VAG 1552). Then switch ignition on and select engine control module with the "Address word" 01.

Connecting scan tool and selecting engine control module. Refer to "VAG 1551 Scan Tool" [1][2][3][4][5]Connecting VAG 1551 Scan Tool

Indicated on display:


Rapid data transfer HELP
Select function XX


- Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.


Indicated on display:


Read measured value block HELP
Input display group number XXX


- Press keys 0, 6 and 2 for the "Display group number 62" and confirm entry with Q key.

Indicated on display: (1-4 = Display zones)


Read measured value block 62 "
1 2 3 4


- Check throttle valve angle at idling stop from sender 1 (G187) in display zone 1
Specification: 3 - 93 %
- Check throttle valve at idling stop from sender 2 (G188) in display zone 2.
Specification: 97 - 3 %
- Depress accelerator slowly to wide open throttle position and observe angles displayed in display zones 1 and 2:
The percentage figure in display zone 1 must increase evenly, although the tolerance range 3 - 93 % will not be fully exploited.
The percentage figure in display zone 2 must decrease evenly, although the tolerance range 97 - 3 % will not be fully exploited.


NOTE:
- The reason why the display in display zone 1 increases and the display in display zone 2 decreases is because the potentiometers (angle senders) in the throttle valve control module run in opposite directions.
- This means that the voltage of one angle sender moves towards 5 volts. (The more the throttle valve is opened the higher the voltage; percentage figure increases).
- Whilst the voltage of angle sender 2 decreases from 5 volts towards 0 volts. (The more the throttle valve is opened the lower the voltage; percentage figure decreases).


If the displays do not indicate as described:
- Press -> key.
- Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
- Switch off ignition.







- Connect test box VAG 1598/31 to control module wiring harness. The engine control module remains disconnected.
- Measure resistance between throttle valve drive and contacts 117 and 118
Specification: 1 - 5 ohms

If the specification is not obtained:
- Replace throttle valve control module (J338).

If the specification is obtained:
- Check voltage supply of throttle valve control module and wiring to control module.
- Check the accelerator pedal position sender.

If the voltage supply and wiring is OK:
- Replace engine electronics control module.

Checking voltage supply and wiring to control module







- Pull the 6-pin connector -2- off the throttle valve control module -1-.
- Connect the multimeter to measure voltage to contacts 2 + 6 of the connector.
- Switch on ignition.
Specification: min. 4.5 V
- Switch off ignition.
- Connect the multimeter to measure voltage to contact 2 of the connector and Ground.
- Switch on ignition.
Specification: min. 4.5 V
- Switch off ignition.

If the specifications are not attained:







- Connect test box VAG 1598/31 to control module wiring harness. The engine control module remains disconnected.
- Check the wiring between test box and connector for open circuit using wiring diagram:
Contact 1 + socket 92
Contact 2 + socket 83
Contact 3 + socket 117
Contact 4 + socket 84
Contact 5 + socket 118
Contact 6 + socket 91
Wire resistance: max. 1.5 ohms
- Additionally check wires for short to one another.
- Additionally check the wiring for short to battery positive or Ground.

If no wiring fault is detected:
- Check engine control module voltage supply. Refer to "Control Module Voltage Supply Check" Testing and Inspection