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 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 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 for Electronic Power Control (EPC) -G186- in the Throttle Valve Control Module - J338-. It is operated by the Engine Control Module (ECM) -J623- and the Accelerator Pedal Position Sensor 1 -G79- /Accelerator Pedal Position Sensor 2 -G185-.

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

• Throttle Drive for Electronic Power Control (EPC) -G186-
• Throttle Drive Angle Sensor 1 for Electronic Power Control (EPC) -G187-
• Throttle Drive Angle Sensor 2 for Electronic Power Control (EPC) -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 are not obtained:

-- 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.

Checking resistance 

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

Specified value: 3.0 to 7.0 Ω (at 20° C)

If the specified value was Not obtained:

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

If the specified value was obtained:

-- Check the voltage supply of the Throttle Valve Control Module -J338- from the Engine Control Module (ECM) -J623- as instructed below.

Checking voltage supply and wiring

-- Switch the ignition ON.

-- Using a multimeter, check the Throttle Valve Control Module -J338- electrical harness connector, terminals 2 to 6 for voltage from the ECM.

Specified value: 4.5 to 5.2 V

-- Switch the ignition OFF.

If the specified value was Not obtained:

Checking wiring 

-- Remove the Engine Control Module (ECM) -J623-. Refer to the Repair information.

-- Using a multimeter, check the Throttle Valve Control Module -J338- electrical harness connector terminals to the Engine Control Module (ECM) -J623- electrical harness connector T60 terminals for an open circuit according to the wiring diagram. Refer to Wiring Diagrams for pin locations.

Throttle Valve Control Module -J338- electrical harness connector terminals	Engine Control Module (ECM) -J623- electrical connector T60 terminals or test box socket
1	27
2	28
3	15
4	12
5	30
6	29

Specified value: 1.5 Ω max.

If the specified value was Not obtained:

-- Check the wiring for an open, high resistance or short to ground.

-- If necessary, repair the faulty wiring connection.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

If no fault is detected in the wiring and the voltage supply was Not OK:

-- Replace the Engine Control Module (ECM) -J623-. Refer to the Repair information.

Final procedures 

After the 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. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .