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Testing idling speed switch > < Testing operation

A3 Mk1

Motronic Injection and Ignition System (4-cyl.)
Testing throttle valve control part
Performing adaption of throttle valve control part

The basic setting function enables the engine control unit to learn the stop positions from the throttle valve control part with the ignition switched off and the engine not running.

If the throttle valve control part -J338 is removed and refitted or replaced, or if the power supply of the engine control unit is interrupted, a basic setting must be performed.

Test conditions

  • ● No faults stored in fault memory
    , interrogating fault memory
  • ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the ignition must be switched on.
    (Connecting fault reader and selecting engine electronics control unit => Page 01-3.)
 
→ Indicated on display:
Rapid data transfer    HELP
Select function XX
  • ‒ Press keys 0 and 4 for the function "Introduction of basic setting" and confirm entry with Q key.
 
→ Indicated on display:
Basic setting    HELP
Input display group number XXX
  • ‒ Press keys 9 and 8 for "Display group number 98" and confirm entry with Q key.
 
→ Indicated on display:
System in basic setting    98    ⇒
    x.xxx V    x.xxx V    Idling ADP.runs

When the Q key is pressed the throttle valve positioner moves to Min., Max. and five intermediate positions, and the control unit records the various throttle valve angles in its non-volatile memory. This process takes no more than 10 seconds. The throttle valve then remains in the start position for a brief period before closing.
 
→ Indicated on display:
System in basic setting    98    ⇒
    x.xxx V    x.xxx V    Idling ADP. O.K.

______________________________________________
 
→ If any of the following messages appears on the display, this means that the adaption procedure has been interrupted.
Basic setting    98    ⇒
X,XXX V    X.XXX V    Idling    ADP.n.O.K.
 
End adaption procedure by pressing the ⇒ key.
Basic setting    98    ⇒
X,XXX V    X.XXX V    Idling    ADP.runs
 
Basic setting    98    ⇒
X,XXX V    X.XXX V    Idling    ERROR
 
Function is unknown or
cannot be carried out at the moment
  • ‒ Interrogate fault memory.
 
→ If no faults are recognised, check whether the idling speed switch opens and closes when the accelerator pedal is operated. Testing idling speed switch => Page 24-59.
No faults recognised    ⇒
 
→ If one of these faults is displayed, check whether the idling speed switch opens and closes when the accelerator pedal is operated. Testing idling speed switch => Page 24-59.
Idling switch does not open    ⇒
Short to earth
 
Idling switch does not close    ⇒
Open circuit
 
→ If this fault is displayed, test the voltage supply to the engine control unit (voltage at terminal 30 on engine control unit has dropped below 10 V).
Voltage supply    ⇒
Signal too small
 
→ If one of the following faults is displayed, test the throttle valve positioner sender -G127 and the throttle valve potentiometer
=> Page 24-61.
Throttle valve positioner sender -G127    ⇒
Signal too small or great
 
Throttle valve potentiometer -G69    ⇒
Signal too small or great
 
Throttle valve positioner sender -G127    ⇒
Implausible signal

Note:

If the basic setting of the control unit is interrupted, the cause could be one of the following:

  • ◆ The throttle valve cannot reach the mechanical idling stop because of a build-up of dirt (e.g. oil carbon deposits) or an incorrectly adjusted accelerator cable.
  • ◆ Battery voltage too low.
  • ◆ Throttle valve control part or wiring is defective.

After an interruption the fault "Basic setting not completed, fault in basic setting" is stored in fault memory. When next switching on ignition the basic setting is automatically performed again.

  • ‒ End the engine basic setting by pressing the⇒ key.
  • ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.

Testing idling speed switch > < Testing operation