Volkswagen Workshop Service and Repair Manuals

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Test box V.A.G 1598/31
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Diode test lamp V.A.G 1527
• ◆ Current flow diagram

Check conditions

• ● The battery voltage must be at least 11.5 V.
• ● Hall sender must be OK, checking
  .
• ● Engine speed sender must be OK, checking Page 24-68 .

Test sequence

• ‒ → Pull 4 pin connector off ignition transformer -arrow-.

Checking voltage supply

Test conditions

• ● → Fuse No. 34 must be OK.

• ‒ → Using multimeter and adapter cables from V.A.G 1594 measure the supply voltage between contacts 2+4 of disconnected connector.
• ‒ Switch on ignition.
       Specification: min. 11.5 V
• ‒ Switch off ignition.

If no voltage is present:

• ‒ → Check wire between 4 pin connector contact 2 and relay plate for open circuit according to current flow diagram.
       Wire resistance: max. 1.5 ω
• ‒ Check wire between 4 pin connector contact 4 and earth for open circuit according to current flow diagram.
       Wire resistance: max. 1.5 ω

Checking activation

• ‒ → Remove cover above camshaft housing -arrows-.

• ‒ → Pull plug -arrows- off all injectors.

• ‒ → Connect diode test lamp V.A.G 1527 with adapter cables from V.A.G 1594 to
       contacts 1 + 4 (ignition output 1),
       contacts 3 + 4 (ignition output 2)
  of disconnected connector.
• ‒ Operate starter and check the ignition signal from engine control unit.
       The LED must flicker
• ‒ Switch off ignition.

If the LED flickers and there is voltage between contacts 2 + 4:

• ‒ Replace ignition transformer (N152)
  , item 2 .

The LED does not flicker:

• ‒ Check wiring => Page 28-16

Checking wiring

• ‒ → Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.

• ‒ → Check wiring for open circuit between test box and 4-pin connector using current flow diagram.
       Contact 1+socket 102
       Contact 3+socket 103
       Wire resistance: Max. 1.5 ω
• ‒ Additionally check wires for short to one another.
       Specification: ∞ω

If no wiring fault is detected and voltage was present between contacts 2+4:

• ‒ Replace engine control unit
  => Page 24-117 .

Checking secondary resistance

• ‒ → Check the secondary winding on terminal 4 between
       Cyl. 1+Cyl. 4,
       Cyl. 2+Cyl. 3.
       Specification: 4.0... 6.0 kω (at 20 °C)

If the specifications are not attained:

• ‒ Replace ignition transformer (N152)
  => Page 28-3 , item 2 .