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
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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-.

Fig 2: Identifying Throttle Valve Control Module J338 Electrical Harness Connector

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-- 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.

Fig 3: Checking Throttle Drive (For Electronic Power Control (EPC)) G186 At Throttle Valve Control Module J338 Terminals 3 To 5 For Resistance

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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.

Fig 4: Checking Connector Terminals 2 To 6 For Voltage

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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