volkswagen Workshop Repair Guides

Volkswagen Workshop Service and Repair Manuals

ABOUT US
Checking modulating piston movement sender G149 and metering adjuster N146 > < Checking voltage supply for diesel direct injection system

Polo Mk3

Checking fuel temperature senderG81
Checking fuel temperature sender -G81-
Special tools and workshop equipment required
t  Adapter cable (68-pin) -V.A.G 1598/18A- or adapter -V.A.G 1598/22-
t  Hand multimeter -V.A.G 1526C- or multimeter -V.A.G 1715-
t  Auxiliary measuring set -V.A.G 1594C-
t  Current flow diagram
Test procedure
–  Connect fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- and select engine electronics control unit with “address word 01”. Engine must be idling. (Connecting fault reader and selecting engine electronics control unit → Chapter.)
   
Indicated on display:
–  Press buttons 0 and 8 for function “Read measured value block” and confirm entry with Q button.
  
Rapid data transfer                 HELP
Select function XX
Indicated on display:
–  Press buttons 0, 0 and 7 for “Display group number 7” and confirm entry with Q button.
  
Read measured value block           HELP
Input display group number XXX
Indicated on display:
–  If no realistic display appears in display zone 1 or a substitute temperature of -5.4°C is displayed, check fuel temperature sender -G81- and line connections to sender as follows:
–  Press → button.
–  Press buttons 0 and 6 for function “End data transfer” and confirm entry with Q button.
–  Switch off ignition.
Engine code AGD (with 68-pin control unit)
  
Read measured value block 7          ->
15.4°C             15.9°C        16.7°C
–  Disconnect connector for fuel temperature sender -G81- (connector to injection pump quantity adjuster).
–  Measure sender resistance at connector contacts 4+7.
Engine codes AGD (with 80-pin control unit), AHG, AKU
  N23-0007
–  Disconnect 10-pin connector for fuel temperature sender -G81- (connector to injection pump quantity adjuster).
–  Measure sender resistance at connector contacts 4+7.
Continuation for all engine codes
  A23-0027
Specification see diagram
Scale A shows resistance values for temperature range 0..50°C and scale B the values for temperature range 50..100°C.
Examples:
t  30 °C corresponds to a resistance of 1500..2000 Ω
t  80 °C corresponds to a resistance of 275..375 Ω
If the specification is not achieved:
–  Renew injection pump → Chapter.
If the specification is attained:
Engine code AGD (with 68-pin control unit)
  N24-0157
–  Connect adapter cable, 68-pin -V.A.G 1598/18A- to control unit wiring harness.
  V29-0062
–  Check lines between adapter cable (68-pin) -V.A.G 1598/18A- and connector for open circuit according to current flow diagram. Contact 7+socket 63 Contact 4+socket 33.
Cable resistance: max. 1.5 Ω.
Engine codes AGD (with 80-pin control unit), AHG, AKU
  N23-0008
–  Connect adapter -V.A.G 1598/22- to control unit wiring harness.
  N23-0197
–  Check lines between adapter -V.A.G 1598/22- and connector for open circuit according to current flow diagram. Contact 7+socket 53 Contact 4+socket 76.
Cable resistance: max. 1.5 Ω.
Continuation for all engine codes
–  Also check wiring for short to one another, short to vehicle earth and short to battery positive.
Specification: ∞ Ω.
If no fault in lines is detected:
–  Renew diesel direct injection system control unit -J248- → Chapter.
  A23-0028

Checking modulating piston movement sender G149 and metering adjuster N146 > < Checking voltage supply for diesel direct injection system