Volkswagen Golf / Golf GTI / Jetta. Manual - part 86

20-64

 

  

  

Electronic Power Control 
(EPC) 

  

  

Function of EPC systems 

 

  

   With the EPC system the throttle valve is not 

operated by the throttle pedal via a cable. 
There is no mechanical connection between 
accelerator and throttle valve.  

  

   The position of the accelerator is transmitted 

to the engine control module by two sensors 
(variable resistors; mounted in one housing) 
which are connected to the accelerator 
pedal.  

  

   The position of the accelerator (drivers 

requirement) is the main input value for the 
engine control module.  

  

   An electric motor (throttle actuator) in the 

Throttle valve control module -J338- 
actuates the throttle valve over the entire 
range of engine speeds and load.  

  

   The throttle valve is operated by the throttle 

actuator under instructions from the engine 
control module.  

  

   When the engine is not running and the 

ignition is switched on the engine control 
module moves the throttle valve exactly as 
prescribed by the accelerator pedal position 
sender. This means that when the 
accelerator is depressed halfway the throttle 
valve positioner opens the throttle valve by 
the same amount, the throttle is then 
approximately half open.  

Electronic Power Control (EPC)

20-65

 

  

   When the engine is running (under load) the 

engine control module can open or close the 
throttle valve independently of the 
accelerator pedal position sender.  

  

   This means that the throttle valve can 

already be completely open even though the 
accelerator pedal is depressed half way. 
This has the advantage of preventing 
throttle losses at the throttle valve.  

  

   This also gives vastly improved fuel 

consumption and exhaust emission levels at 
certain load conditions.  

  

   It is wrong to believe that EPC only consists 

of two components. It is a system which 
contains all components needed to help 
determine, regulate, and supervise the 
throttle valve position (e.g. the throttle 
position sensor which measures the 
accelerator position, the throttle valve 
control module, the EPC indicator lamp, the 
engine control module).  

Electronic Power Control (EPC)

20-66

 

  

Electronic 
Power 
Control 
(EPC), 
servicing 

 

 

Repair 

1 - Mounting 

bracket 

2 - Connector 

 Black, 

6-pin 

 Gold 

plated 
contacts 

3 - 10 Nm 

4 - Throttle 

Position 
(TP) 
sensor -
G79- 

 Not 

adjustable 

 TP sensor 

passes 
driver's 
requirements 
on to engine 
control 
module 

 Remove 

footwell 
cover to 
remove 
sensor 

 Checking 

 

Page 

20-67

 

 If replaced 

adapt control 
module for 
automatic 
transmission: 

Electronic Power Control (EPC)

Manual, 5 Spd. 
Automatic 
Transmission 
09A On Board 
Diagnostic 
(OBD); Repair 
Group 01

 

5 - Bracket 

 For 

footwell 
cover 

 Clipped 

onto 
accelerator 
pedal 

Electronic Power Control (EPC)