Volkswagen Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ Test box V.A.G 1598/18
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Diode test lamp V.A.G 1527
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Check conditions

• ● Hall sender OK.
• ● Ignition transformer OK.

Checking voltage supply

• ‒ Pull 3 pin plug off ignition transformer.
• ‒ → Connect multimeter to measure voltage with aux. cables from V.A.G 1594 to the contacts 1+3 of the disconnected plug.
• ‒ Switch on ignition.
       Specification: Min. 11 V

If no voltage is present:

• ‒ Switch off ignition.
• ‒ Check wire between 3 pin connector contact 1 and earth for open circuit according to current flow diagram.
       Wire resistance: Max. 1.5 ω
• ‒ Check wire between 3 pin connector contact 3 and relay plate for open circuit according to current flow diagram.
       Wire resistance: Max. 1.5 ω

Checking activation

• ‒ Disconnect plug for injector and intake air preheating from the injection unit.

• ‒ → Connect diode test lamp V.A.G 1527 with aux. cables from V.A.G 1594 and adapters V.A.G 1594/15 to contacts 2+3 of the plug.
• ‒ Operate starter and check ignition signal from Mono-Motronic control unit.
       LED must flicker

The LED does not flicker:

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.
• ‒ Check wire between test box socket 24+3 pin connector contact 2 for open circuit according to current flow diagram.
       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 1+3:

• ‒ Renew Mono Motronic control unit (J257)
  =>Page 24-6 , item 2 .

If the voltage supply and activation is OK.:

• ‒ Connect 3 pin plug and H.T. cable to ignition transformer.
• ‒ → Connect diode test lamp with aux. cables and clamps to the contacts 1 and 15 on ignition transformer.

• ‒ Operate starter.
       The LED must flicker,
  if necessary renew output stage.