Volkswagen 1.9 tdi, Owner'S Manual, Page: 46 / 67

42
Engine Management
Cruise control switch
The signal generated by the cruise control
switch tells the Diesel Direct Fuel Injection
Engine Control Module J248 that the cruise
control system has been activated.
Three-phase AC generator terminal DF
The signal supplied by generator terminal
DF indicates the load state of the three-
phase AC generator to the Diesel Direct
Fuel Injection Engine Control Module J248.
Depending on available capacity, the Diesel
Direct Fuel Injection Engine Control Module
J248 can switch on one, two, or three Glow
Plugs (Coolant) Q7 of the coolant auxiliary
heater via the Relay for Preheating Coolant,
Low Heat Output J359 and the Relay for
Preheating Coolant, High Heat Output J360.
CAN data bus
The Diesel Direct Fuel Injection Engine
Control Module J248, the ABS Control
Module with EDL/ASR/ESP J104, and the
Transmission Control Module J217
interchange information along a
CAN data bus.
Additional Input Signals
Road speed signal
The Diesel Direct Fuel Injection Engine
Control Module J248 receives the road
speed signal from the vehicle speed sensor.
This signal is used to calculate various
functions, including cooling fan run-on
and engine shudder damping when
shifting gears.
It is also used to check the cruise control
system for proper functioning.
Air conditioner compressor ready
The air conditioner switch sends Diesel
Direct Fuel Injection Engine Control Module
J248 a signal indicating that the air
conditioner compressor will shortly be
switched on.
This enables the Diesel Direct Fuel Injection
Engine Control Module J248 to increase
the engine idle speed before the air
conditioner compressor is switched on to
prevent a sharp drop in engine speed when
the compressor starts up.
SSP209/083