SEAT Workshop Service and Repair Manuals

Special tools, testers, measuring instruments and auxiliary items required

• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
• ◆ Test box V.A.G 1598/18
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Engine codes AFN, AVG

Engine codes AHU, 1Z

Test sequence

• ‒ 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 engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit .)

• ‒ Press keys 0 and 4 for the function "Introduction of basic setting" and confirm entry with Q key.

• ‒ Press key 0 three times for "Display group number 0" and confirm entry with Q key.

The commencement of injection in display zone 2 is dependent on the fuel temperature in display zone 9.

• → A - Display zone 2 commencement of injection
  B - Display zone 9 fuel temperature
  C - Specified range for commencement of injection

Example:

The numerical value 90 in display zone 9 (B) corresponds to a numerical value range of 34...73 in display zone 2 (A).

If commencement of injection is not in specified range -C-:

• ‒ Adjust commencement of injection .

If commencement of injection is in specified range -C-:

• ‒ Press C key.
• ‒ Press keys 0, 0 and 4 for "Display group number 4" and confirm entry with Q key.

• The displays in display zones 3 and 4 must fluctuate within following control range:
• ‒ Specification display zone 3
      7...9°BTDC
• ‒ Specification display zone 4
      lower range 2...5%
      upper range 90...95%

Because the fault reader display is slow the displayed figures vary greatly. Therefore ensure that only in
display zone 3 the lowest figure lies between 7 and 9
and in display zone 4 the lowest figure lies between 2 and 5, and the highest figure lies between 90 and 95.

If the specifications are not obtained:

• ‒ Check commencement of injection valve as follows:
• ‒ Press the ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.

• ‒ Disconnect connector on injection pump =>Fitting locations overview, Page 23-4.
• ‒ → Measure resistance between connector contacts 9+10.
      Specification: 12 ... 20 ω

If the specification is not obtained:

• ‒ Replace commencement of injection valve (N108)
  .

If the specification is obtained:

• ‒ Remove dash panel insert:

=> Electrical system; Repair group 90; dash panel insert; removing and installing dash panel insert

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.

• ‒ → Check wiring between test box and 3 pin connector for open circuit according to current flow diagram.
      Contact 9+ socket 51
      Contact 10+ socket 68
      Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another, to vehicle earth and to battery positive.
      Specification: ∞ω

If no wiring fault is detected:

• ‒ Renew Diesel direct injection system control unit (J248) => Page 23-5, item 9.

Engine codes AHU, 1Z

The control range of the injection adjuster can be checked with help of final control element test and at the same time calling-up measured value block 04. To do this it is required to activate the control element Commencement of injection valve -N108 and then exiting the final control element test with key -C-. Using this sequence the commencement of injection valve continues to be pulsed so that with help of measured value block 04 (display zone 3) the injection adjuster control range can be read.

Test sequence

• ‒ 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 engine must be running at idling speed.
  (Connecting fault reader and selecting engine electronics control unit => Page 01-4.)

• ‒ Press keys 0 and 3 for the function "Final control diagnosis".

Note:

The individual control elements are only activated for 30 seconds. Within this period various work sequences must be carried out with the fault reader unit as well as reading the measured values. Therefore read the following work sequence first to become conversant with the procedure.

• ‒ Confirm input with Q key.

• ‒ Press C key.
• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 0 and 4 for "Display group number 4" and confirm entry with Q key.

• The displays in display zones 3 and 4 must fluctuate within following control range:
• ‒ Specification display zone 3
      lower range 3°ATDC...4.0°BTDC
      upper range 14.0...17.4°BTDC
• ‒ Specification display zone 4
      lower range 2...5%
      upper range 90...95%

Because the fault reader display is slow the displayed figures vary greatly. Therefore ensure that only in
display zone 3 the lowest figure lies between 1.0 and 4.0 and the highest figure lies between 14.0 and 17.4
and in display zone 4 the lowest figure lies between 2 and 5, and the highest figure lies between 90 and 95.

If the specifications are not obtained:

• ‒ Check commencement of injection valve as follows:
• ‒ Press the ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.

• ‒ Switch off ignition.
• ‒ Disconnect connector on injection pump =>Fitting locations overview, Page 23-4.
• ‒ → Measure resistance between connector contacts 2 + 3.
      Specification: 12 ... 20 ω

If the specification is not obtained:

• ‒ Replace commencement of injection valve (N108)
  .

If the specification is obtained:

• ‒ Remove dash panel insert:

=> Electrical system; Repair group 90; dash panel insert; removing and installing dash panel insert

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.

• ‒ → Check wiring between test box and 3 pin connector for open circuit according to current flow diagram.
      Contact 2+ socket 51
      Contact 3+ socket 68
      Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another, to vehicle earth and to battery positive.
      Specification: ∞ω

If no wiring fault is detected:

• ‒ Renew Diesel direct injection system control unit (J248) => Page 23-5, item 9.