audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

ABOUT US
Functional description of auxiliary heater > < Characteristic resistance curve of temperature sensor G18

A3 Mk2

Test step 3 (fuel pre-heating heater elementZ66 and fuel shut-off valveN109)
Test step 3 (fuel pre-heating heater element -Z66- and fuel shut-off valve -N109-)
  Note
t  The fuel pre-heating heater element -Z66- is only fitted on the auxiliary heater version for diesel fuel (not fitted on all vehicles at start of production, introduced gradually).
t  The installation of a fuel shut-off valve -N109- is currently only planned for vehicles with diesel engine (only installed on VW vehicles; introduction for Audi vehicles not yet finalised) → Electronic parts catalogue
t  Currently no auxiliary heater with a fuel shut-off valve -N109- is installed in Audi A3 vehicles during production (introduction not yet finalised). However it is possible that individual vehicles have been retro-fitted with an auxiliary heater with a fuel shut-off valve -N109-; therefore it is important to pay attention to the correct version.
   
Vehicle diagnostic, testing and information system -VAS 5051 A-, measurement mode: Multimeter, resistance measurement (0...100 Ω)
Test stepConnection on heaterComponent(s) checked
l  Test requirements
–  Additional steps
SpecificationMeasures to be taken if reading does not match specification
3.1Connector B, contacts 3 and 4Fuel pre-heating heater element -Z66- and corresponding wiring 
–  Greater than 1 and less than 15 Ω
–  Renew burner element with glow plug with flame monitor -Q8- and fuel pre-heating heater element -Z66-
3.2Connector B, contact 3 and auxiliary heater housing  
–  ∞ Ω.
–  Renew burner element with glow plug with flame monitor -Q8- and fuel pre-heating heater element -Z66-

  Note
t  If resistance at connector -B- between contacts “3” and “4” is greater than 5 kohms or less than 50 mohms, fault is detected by auxiliary heater control unit -J364-.
t  If voltage of 9 V is applied to fuel pre-heating heater element -Z66-, power input at low ambient temperatures is up to approx. 4.5 A (power input decreases as soon as heater element warms up).
t  Currently the glow plug with flame monitor -Q8- and the fuel pre-heating heater element -Z66- (and, if fitted, the fuel shut-off valve -N109-) can only be renewed together with the burner element (electrical wires welded in a joint grommet) → Chapter.
t  The installation of a fuel shut-off valve -N109- is currently only planned for vehicles with diesel engine (only installed on VW vehicles; introduction for Audi vehicles not yet finalised) → Chapter and → Electronic parts catalogue.
t  Currently no auxiliary heater with a fuel shut-off valve -N109- is installed in Audi A3 vehicles during production (introduction not yet finalised). However it is possible that individual vehicles have been retro-fitted with an auxiliary heater with a fuel shut-off valve -N109-; therefore it is important to pay attention to the correct version.
   
Vehicle diagnostic, testing and information system -VAS 5051 A-, measurement mode: Multimeter, resistance measurement (0..0.20 Ω)
Test stepConnection on heaterComponent(s) checked
l  Test requirements
–  Additional steps
SpecificationMeasures to be taken if reading does not match specification
3.3Connector B, contacts 1 and 2Fuel shut-off valve -N109- and corresponding wiring 
–  Greater than 110 and less than 150 Ω
–  Renew burner element with glow plug with flame monitor -Q8-, fuel pre-heating heater element -Z66-
3.4Connector B, contact 1 and auxiliary heater housing  
–  ∞ Ω.
and fuel shut-off valve -N109-

  Note
The fuel shut-off valve -N109- closes off the fuel pipe when the auxiliary heater is switched off. After switching on the auxiliary heater (shortly before the metering pump -V54- is activated), the auxiliary heater control unit -J364- supplies power to the fuel shut-off valve -N109-; the fuel shut-off valve -N109- opens and allows fuel to flow into the auxiliary heater.
   

Functional description of auxiliary heater > < Characteristic resistance curve of temperature sensor G18