Throttle Valve Control Module J338 , Checking
Throttle Valve Control Module J338, Checking
Special tools, testers and auxiliary items required
- Multimeter V.A.G 1526 or equivalent.
- Test Box 105 Pin VAG1598/42.
- Adapter Lead Vag1598/39 VAG1598/39.
- Adapter cable V.A.G 1598/39-1.
NOTE: Use only gold-plated terminals when servicing terminals in harness connector of Throttle Valve Control Module J338.
Test requirements
- Fuses for Engine Control Module (ECM) J623 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 (GND) connections between engine/transmission/chassis OK.
- Throttle valve must not be damaged or dirty.
- Coolant Temperature at least 80 degrees C.
Function
Throttle valve operation occurs via an electric motor ( Throttle Drive (for Electronic Power Control (EPC)) G186 ) in the Throttle Valve Control Module J338 and is operated by the Engine Control Module (ECM) J623 according to the signals supplied by the Throttle Position (TP) Sensor G79 / Accelerator Pedal Position Sensor 2 G185.
Components of Throttle Valve Control Module J338 :
- 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
Function test
- Connect the diagnostic tester.
- Switch ignition on.
- Select "Diagnostic mode 1: Check measured values".
- Select the measuring value "PID 17: Throttle valve position" .
- Check specified value of throttle valve position (absolute) at idle stop:
- Slowly depress accelerator pedal up to Wide Open Throttle (WOT) stop while observing the percentage display. The percentage display must increase uniformly.
- Check specified value of throttle valve position (absolute) at Wide Open Throttle (WOT) stop:
- End diagnosis and switch ignition off.
If specified values are not obtained:
- Remove Throttle Valve Control Module J338 far enough so that terminals of connector on Throttle Valve Control Module J338 are reached.
- Disconnect the electrical harness connector - 2 - from the Throttle Valve Control Module J338 .
Checking resistance
- Using the Multimeter V.A.G. 1526 A or equivalent, check the resistance of Throttle Drive (for Electronic Power Control (EPC)) G186 at Throttle Valve Control Module J338 between terminals 3+5.
Specified resistance 1.5 Ohms max.
If the specification is not obtained:
- Replace Throttle Valve Control Module J338.
If the specification is obtained:
- Check voltage supply of the Throttle Valve Control Module J338 to the Engine Control Module (ECM) J623.
- Check Throttle Position (TP) Sensor G79 / Accelerator Pedal Position Sensor 2 G185. Testing and Inspection
Checking voltage supply and wiring
- Switch ignition on.
- Using the Multimeter V.A.G. 1526 A or equivalent, check the voltage of Throttle Drive (for Electronic Power Control (EPC)) G186 at Throttle Valve Control Module J338 between terminals 2+6.
Specified value: at least 4.5 V
- Switch ignition off.
- Connect the Test Box 105 Pin VAG1598/42 to the wiring harness of the Engine Control Module (ECM) J623.
- Using the Test Box 105 Pin VAG1598/42 and Multimeter V.A.G 1526 A or equivalent, check the following wiring connections for an open circuit.
Terminal Test box socket
1 12
2 28
3 30
4 27
5 15
6 29
Specified resistance 1.5 Ohms 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 found in the wiring:
- Replace the Engine Control Module (ECM) J623.
Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.
- End diagnosis and switch the ignition off.