Throttle Valve Control Module, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test Requirements 

• The Engine Control Module (ECM) -J623- fuses OK.
• Battery voltage at least 12.5 V.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• Parking brake applied.
• 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 Throttle drive (power accelerator actuation) -G186-) in Throttle Valve Control Module - J338-. It is operated by Engine Control Module (ECM) -J623- according to specifications of Throttle Position (TP) Sensor -G79- /Accelerator Pedal Position Sensor 2 -G185-.

Components of Throttle Valve Control Module -J338- :

• Throttle drive (power accelerator actuation) -G186-
• Angle Sensor 1 -G187-
• Angle Sensor 2 -G188-

Test Procedure 

-- Perform a preliminary check to verify the customer's complaint. Refer to PRELIMINARY CHECK

-- 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		12 to 16%

-- Slowly depress the accelerator pedal to Wide Open Throttle (WOT) stop while observing the percentage display. The percentage display must increase uniformly. On vehicles with automatic transmissions do not press down beyond the kickdown point when doing this.

-- 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 to 88%

-- Switch the ignition off.

If the specified values are not obtained.

Checking voltage supply

-- Remove the rear engine cover -arrows-.

-- Disconnect the electrical harness connector -1- at the Throttle Valve Control Module -J338-.

-- Switch the ignition on.

-- Using the Multimeter --, check the electrical harness connector for voltage.

Throttle Valve Control ModuleJ338Electrical Harness Connector terminal	Specified value
2 + Ground (GND)	about 5 V
2 + 6	about 5 V

-- Switch the ignition off.

If the specified values are not obtained.

Checking wiring connections

If the manufacturers test box is being used, perform the following step.

-- Install the test box VAG1598/42. Refer to Component Locations Overview .

If the manufacturers test box is not being used, perform the following step.

-- Remove the Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REPLACING .

-- Using a Multimeter --, check the Accelerator Pedal Position Sensor 2 -G185- at Throttle Valve Control Module -J338- electrical harness connector terminals to the Engine Control Module (ECM) -J623- electrical harness connector terminals for resistance.

Throttle Valve Control Module -J338- Electrical Harness Connector Terminal	Engine Control Module (ECM) -J623- Electrical Harness Connector Terminal
1	13
2	14
3	15
4	28
5	30
6	12

Specified value: 1.5 Ω max.

If the specification is not obtained:

-- Check the wiring for a short circuit to Battery positive (+) or an open circuit.

-- If necessary, repair the wiring connection.

If no malfunctions are detected in the wiring and if the voltage supply was OK:

-- Replace the Throttle Valve Control Module -J338-.

-- After replacing theThrottle Valve Control Module -J338-, it must be adapted. For this purpose switch on ignition for at least 30 Sec. without starting the engine or depressing the accelerator pedal.

If no malfunctions are detected in the wiring and if the voltage supply was not OK:

-- Replace the Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REPLACING .

-- Switch the ignition off.

The Engine Control Module (ECM) -J623- now requires approx. 3 Sec. to store the learned value. At this time, the ignition must not be switched on again.

Assembly is performed in reverse order of removal, note the following:

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. Refer to READINESS CODE .