With Manufacturer's Scan Tool
Throttle Valve Control Module -J338-, Checking
Components of throttle valve control module -J338-: Throttle valve drive -G186-, Angle sensor 1 for throttle valve drive -G187-, and Angle sensor 2 for throttle valve drive -G188-.
NOTE: When the throttle valve control module is replaced, it is absolutely necessary to adapt the new control module to the Engine Control Module (ECM).
In vehicles with automatic transmissions the transmission control module must also be adapted.
Special tools and equipment
- V.A.G1551 scan tool (or VAG1552 mobile scan tool) with VAG1551/3 cable
- VAG1598/31 test box
- Multimeter Fluke 83 or equivalent
- VAG1594 connector test kit
- Wiring diagram
Test requirements
- DTC memory was checked, check DTC memory of Engine Control Module (ECM).
- Throttle valve must not be damaged or dirty.
- All electrical consumers like, for example, lights and rear window heating must be switched off.
- If vehicle is equipped with an A/C system, it must be switched off.
- Battery voltage must be at least 11.5 volts.
- Coolant temperature must be at least 80°C, See Display group 04, display field 3
Test sequence
- Connect V.A.G 1551 scan tool (VAG1552). Then switch ignition on and select the Engine Control Module (ECM) using address word 01 [1][2]Reading and Clearing Diagnostic Trouble Codes
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.
Indicated on display:
Read measuring value block
Enter display group number XXX
- Press 0, 6 and 2 for the function "display group number 62", and then press Q to exit from input mode.
Indicated on display: (1 to 4 = display fields)
Read measuring value block 62 ->
1 2 3 4
- Check throttle angle of sensor 1 -G187- at idle stop in display field 1 Specification: 3 to 16%
- Check throttle angle of sensor 2 - G188- at idle stop in display field 2 Specification: 97 to 82%
- Press gas pedal slowly until it reaches Wide Open Throttle (WOT) position, and observe angle display in display fields 1 and 2:
Percent indication in display field 1 must rise uniformly. In the process, the tolerance range of 3 to 93% is not completely utilized.
Percent indication in display field 2 must decrease uniformly. The tolerance range 97 to 3% is not used completely during this.
NOTE:
The value indicated in display field 1 increases, but the value indicated in display field 2 decreases, because the potentiometers (angle sensors) in the throttle valve control module run in opposite directions.
The percent indications in display fields 1 and 2 must always amount to approx. 100% together.
This means that the voltage tap of angle sensor 1 runs from 0 to 5 volts. (The more the throttle valve is opened, the larger the voltage; percent indication climbs).
The voltage tap of angle sensor 2 runs from 5 to 0 volts. (The more the throttle valve is opened, the lower the voltage; the percentage decreases).
If indications do not resemble description:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06. Press -Q- button to confirm input.
- Switch ignition off.
- Remove wiper arms and wind cowl:
- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.
- Measure resistance of throttle valve drive between test box sockets 117 + 118
Specification:1 to 5 Ohms
If specified value is not obtained:
- Replace throttle valve control module -J338-.
- Check DTC memory, repair any malfunctions and then erase DTC memory, Checking and erasing DTC memory.
If specified value is obtained:
- Check voltage supply of throttle valve control module and wiring to control module.
- Check Throttle Position (TP) sensor and sensor 2 for accelerator pedal position.
If voltage supply and wires are OK:
- Replace Engine Control Module (ECM).
Checking voltage supply and wiring to control module
- Disconnect 6-pin connector -2- at the throttle valve control module.
- Connect multimeter to terminals 2 + 6 of connector to make voltage measurement.
- Switch ignition on.
Specification: at least 4.5 V
- Switch ignition off.
- Connect multimeter to terminal 2 of connector and Ground (GND) for voltage measurement.
- Switch ignition on.
Specification: at least 4.5 V
- Switch ignition off.
If specified values are not obtained:
- Remove wiper arms and wind cowl:
- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.
- Check for open circuits in wires between test box and connector according to wiring diagram:
Terminal 1 and test box socket 92
Terminal 2 and test box socket 83
Terminal 3 and test box socket 117
Terminal 4 and test box socket 84
Terminal 5 and test box socket 118
Terminal 6 and test box socket 91
Wire resistance: max: 1.5 Ohms
- Also check wires for short circuits to each other, to B+ and to Ground (GND). Specification: Infinity Ohms
NOTE: Use only gold-plated terminals when servicing the harness connector.
If wiring is OK:
- Check voltage supply of Engine Control Module (ECM). Engine Control Module (ECM) Voltage Supply, Checking