Touareg: 2006 V8
Join Date: Sep 2006
Location: Wytheville VA USA
Second Vehicle: 2004 V6
Thanked 313 Times in 273 Posts
The Touareg Electrical System Design and Function
Self-Study Programme 298
Priming function of electrical fuel pump
The petrol engines of the Volkswagen Touareg all feature a priming function of the fuel pump so that enough pressure in the fuel lines can be built up.
When the driver's door is opened and terminal 15 is closed, a signal is sent via the CAN bus from the entry and start authorisation control unit J518 (terminal 15 off), a signal is also sent from the driver's door control unit J386 (driver's door opened) and, for reasons of safety, a discreet signal (status of terminal 15) is sent to the onboard power supply control unit J519. This then actuates the relay to prime the fuel pump for approx. 2 seconds. The priming function of the fuel pump is stopped when the ignition is switched on. Continued actuation is done through the engine control unit.
If the driver's door stays open, the actuation is repeated a maximum of three times in intervals.
Timed actuation from the onboard power supply control unit prevents continued actuation of the fuel pump if the driver's door is opened and closed a number of times in short intervals.
If with the ignition switched on a crash is detected, a signal is sent from the airbag control unit J234 via the CAN bus and the fuel pump is switched off immediately. After about 5 seconds it can be activated again by switching the ignition off and on.
Electric circuit:Onboard power supply management Key
G6 Fuel pump
J17 Fuel pump relay
J386 Driver's door control unit
J518 Entry and start authorisation control unit
J519 Onboard power supply control unit
J623 Engine control unit