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Checking crash signal wire > < Checking air conditioner compressor cut-out

A3 Mk1

Checking power assisted steering pressure switchF88
Checking power assisted steering pressure switch -F88-
The function of the power assisted steering pressure switch is to stabilise the idling speed when the steering wheel is on full lock (left or right).
Test sequence
–  Connect up the vehicle diagnostic and service information system -VAS 5052- and select the engine electronics control unit. Engine must be idling.
–  Select the function “Read measured value block”.
–  Select “Display group number 056”.
–  Check the power assisted steering pressure switch in display zone 4.
   
 Display zones
 1234
Display Group 056: Idling speed stabilisation with engine idling at normal operating temperature
Displayxxx rpmxxx rpmx.x %X X X X X
DisplayActual engine speedSpecified engine speedIdling speed control
torque change		Operating statuses
Operating range   0XXXX
1XXXX
Specification   
l  Steering in straight ahead position or slight steering angle:
0XXXX
    
l  Full steering lock or rapid steering action:
1XXXX
Note   Value:
X = no significance

If display differs from specification described above: check switch
Checking switch
–  Unplug the connector at the power assisted steering pressure switch -F88- at the power steering pump.
   
–  Connect multimeter to switch (resistance measurement range).
–  Start engine.
t  Specification: ∞ Ω (no continuity)
–  Turn steering wheel to full lock (left and right).
t  Specification: approx. 0 Ω
If display does not change:
–  Replace the power assisted steering pressure switch -F88-.
If the display changes:
–  Check the wiring.
Checking wiring
–  Connect the test box -V.A.G 1598/31- to the wiring harness to the engine control unit, but do not connect the actual engine control unit → Chapter.
  A24-0199
–  Check for open circuit and short to earth or positive in the following wiring:
  A24-0331
Connector
Contact		Test box -V.A.G 1598/31-
Socket
149
250

–  Eliminate open circuit in wiring/short circuit if necessary.
   

Checking crash signal wire > < Checking air conditioner compressor cut-out