Electronic Accelerator Control (E-Gas), Checking
1 - Bracket
- Removing and installing. See Brake System ABS, ABS/EDL, Repair Group.
2 - Connector
- Black, 6-pin
3 - 10 Nm
4 - Throttle Position (TP) sensor -G79- and -G185-
- When removing remove footwell cover
5 - Retainer
- For footwell cover
- Clipped onto accelerator pedal
E-Gas system, function
In the E-Gas system, the throttle valve is not operated via cable from the accelerator. There is no mechanical connection between accelerator and the throttle valve.
The position of the accelerator pedal is communicated to the engine control module via two sensors for accelerator pedal position (variable resistances, stored in one housing) that are connected with the accelerator pedal.
The position of the accelerator (drivers intention) is the main input value for the Engine Control Module (ECM).
The throttle valve is operated over the entire RPM and load range via electric motor (throttle valve actuator) in the throttle valve control module.
The throttle valve is operated by the throttle valve actuator according to the specifications of the Engine Control Module (ECM).
When the engine is not running and the ignition is switched on, the ECM activates the throttle valve actuator exactly according to the specifications of the accelerator pedal position sensor. This means, if the accelerator pedal is depressed halfway, the throttle valve actuator opens the throttle valve to the same degree; the throttle valve is then opened halfway.
When the engine is running (under load) the Engine Control Module (ECM) can open and close the throttle valve independently of the accelerator pedal position sensor.
In this way, the throttle valve can already be completely open even though the accelerator pedal has only been depressed half way.
This also gives vastly improved fuel consumption and exhaust emission levels under certain load conditions.
The torque required by the engine can be produced by the ECM by optimizing the combination of throttle valve cross-section and charge pressure.
It is incorrect to believe that the E-Gas is comprised of only one or two components. The E-Gas is a system containing all components which have an influence, control or monitor the position of the throttle valve, e.g. the accelerator pedal position sensor, the throttle valve control module, the Electronic Power Control (EPC) warning light, the Engine Control Module (ECM).
Electronic accelerator warning light
NOTES: The component designated as the Fault Light for Power Accelerator Activation -k132- is known also as the EPC warning light.
Special tools and equipment
- V.A.G 1526 or fluke 83 multimeter
- V.A.G 1594 A Adapter set.
- V.A.G 1598/31 Test box
- Wiring diagram
Checking function of EPC warning light
- Switch ignition on.
- The EPC warning light must light up.
- Start engine and run at idling speed.
- The EPC warning light must go out when no EPC malfunction has been stored.
EPC warning light does not light up
- Connect test box V.A.G 1598/31 to control module wiring harness (The engine control module remains disconnected).
- Bridge test box sockets 1 + 48 using cable from V.A.G 1594.
- Switch ignition on.
- The EPC warning light must light up.
If the EPC warning light does not light up:
- Switch ignition off.
- Remove instrument cluster and check bulb and its voltage supply.
If no malfunction is found:
- Check wiring for open circuit between test box socket 48 and instrument cluster according to wiring diagram.
If no wiring malfunction is detected:
- Replace Engine Control Module (ECM).
EPC warning light is lit continuously
- Connect test box V.A.G 1598/31 to control module wiring harness (The engine control module remains disconnected).
- Check wiring for short circuit to Ground between test box socket 48 and instrument cluster according to wiring diagram.
If no wiring malfunction is detected:
- Replace Engine Control Module (ECM).