Throttle Valve Control Module, Checking: Notes

Observe all safety precautions: SAFETY PRECAUTIONS 

View clean working conditions: CLEAN WORKING CONDITIONS 

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Motronic Engine Control Module (ECM) - J623- fuses OK.
  Fig 1: Identifying Fuses On E-Box In Engine Compartment, Left Side

  Courtesy of AUDI OF AMERICA, LLC
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• A/C switched off.
• Ground (GND) connections between engine/transmission/chassis OK.
• Throttle valve must not be damaged or dirty.
• Coolant Temperature at least 80° C.

Function 

Throttle valve operation occurs by an electric motor (Electronic Power Control (EPC) Throttle Drive -G186-) in the Throttle Valve Control Module - J338-. It is operated by the Motronic Engine Control Module (ECM) -J623- and the Throttle Position (TP) Sensor -G79- /Accelerator Pedal Position Sensor 2 -G185-.

The Throttle Valve Control Module -J338- is made up of the following components:

• Electronic Power Control (EPC) Throttle Drive -G186-
• Electronic Power Control (EPC) Throttle Drive angle sensor 1 -G187- Electronic Power Control (EPC) Throttle Drive angle sensor 1 -G187-
• Electronic Power Control (EPC) Throttle Drive Angle Sensor 2 -G188-

The Throttle Valve Control Module -J338- cannot be serviced separately and must be serviced as a unit.

Test procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start diagnosis 

-- Connect the scan tool.

-- Switch ignition on.

-- Using the scan tool, check the throttle valve position (absolute) at idle stop:

Diagnostic text		Specified value
Throttle valve position (absolute)
Idle stop		3.0 to 25.0%

-- Slowly depress the accelerator pedal to Wide Open Throttle (WOT) stop while observing the percentage display. The percentage display must increase uniformly.

-- Using the scan tool, check the throttle valve position (absolute) at Wide Open Throttle (WOT) stop:

Diagnostic text		Specified value
Throttle valve position (absolute)
Wide Open Throttle (WOT) stop		84.0 to 97.0%

-- Switch ignition off.

If the specified values were obtained:

If the test results indicate no monitor failures: The fault may not be active at this time.

-- Check the wiring connection for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

-- Road Test the vehicle to insure system is operating within normal specifications

-- Go to Final procedures

If the specified values were Not obtained:

Checking resistance 

-- Remove the Throttle Valve Control Module -J338 - far enough so that the electrical connector terminals are reached.

-- Disconnect the Throttle Valve Control Module -J338- electrical harness connector -arrow-.

-- Using a Multimeter, check the Electronic Power Control (EPC) Throttle Drive -G186- at the Throttle Valve Control Module -J338- terminals 3 to 5 for resistance.

Specified value: 1.0 to 5.0 Ω (at 20° C)

If the specified value was Not obtained:

-- Replace the Throttle Valve Control Module - J338-. Refer to appropriate service information.

-- Go to Final procedures

If the specified value was obtained:

-- Check the voltage supply of the Throttle Valve Control Module -J338- to the Motronic Engine Control Module (ECM) -J623-.

-- Switch the ignition on.

-- Using a Multimeter, check the Electronic Power Control (EPC) Throttle Drive -G186- at the Throttle Valve Control Module -J338- electrical harness connector terminals 2 to 6 for voltage.

Specified value: near 5.0V

-- Switch the ignition off.

-- Continue test according to the following table:

Value	Cause	Test
If the specified value was not obtained:	Open or shorted circuit	Checking wiring
If the specified value was obtained:	Check reference wiring	Checking wiring