Throttle Valve Control Module, Checking
Use only gold-plated terminals when servicing terminals in harness connector of Throttle Valve Control Module -J338-.
Special tools and workshop equipment required
- Multimeter.
- Wiring diagram.
Test requirements
- The Motronic 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 referred to as the Throttle Drive Motor -G186- located in the Throttle Valve Control Module - J338-. It is controlled by the Motronic Engine Control Module (ECM) -J623- with input from the Accelerator Pedal Position Sensor 1 -G79- /Accelerator Pedal Position Sensor 2 -G185- and throttle drive angle sensors.
The Throttle Valve Control Module -J338- is made up of the following components:
- Throttle Drive Motor -G186-
- Throttle Drive Angle Sensor 1 -G187-
- 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) | ||||
|
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) | ||||
|
84.0 to 97.0% | |||
-- Switch ignition Off.
If the specified value was 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 -arrow-.
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: 1.0 to 5.0 Ω (at 20° C)
If the specified value was Not obtained:
-- Replace the Throttle Valve Control Module - J338-.
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-.
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.
Specified value: at least 4.5 V
-- Switch the ignition Off.
If the specified value was Not obtained:
Checking wiring
-- Remove the Motronic Engine Control Module (ECM) -J623-.
-- Using a multimeter, check the Throttle Valve Control Module -J338- electrical harness connector terminals to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T60 terminals for an open circuit. Refer to appropriate SYSTEM WIRING DIAGRAMS information.
| Throttle Valve Control Module -J338- electrical harness connector terminals | Motronic Engine Control Module (ECM) -J623- electrical connector T60 terminals |
|---|---|
| 1 | 41 |
| 2 | 12 |
| 3 | 1 (Golf) or 17 (EOS) |
| 4 | 24 |
| 5 | 16 |
| 6 | 44 |
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 malfunction is detected in the wiring and if the voltage supply was Not OK:
-- Replace the Motronic Engine Control Module (ECM) -J623-.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .