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Volkswagen Passat Workshop Service and Auto Repair Manuals

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Interrogating fault memory > < Technical data of self diagnosis

Connecting fault reader to engine control unit

Motronic injection and ignition system (4-Cyl.)
Self diagnosis
Connecting fault reader V.A.G 1551 and selecting engine electronics control unit

Test conditions

  • ● Battery voltage OK.
  • ● Fuse 22 OK.
  • ● Earth connections on engine and gearbox OK.
    (Earth connection engine: , Item 18 ).
 
N29-0002
  • ‒ → Unclip cover for diagnostic connections.
  • ‒ Connect fault reader V.A.G 1551 with cable V.A.G 1551/3.
  • ‒ Depending upon desired function:
    Switch on ignition
         or
    Start engine.
  • ‒ Operate fault reader taking into account the information on the display:
  • ‒ Input 1 for "Rapid data transmission".
  • ‒ Input 01 for address word "Engine electronics" and confirm with Q.
 
→ The fault reader V.A.G 1551 display will show the control unit identification, e.g.:
037 906 258 AM     ENGINE     1.6ltr. 4-Cyl. ⇒
Coding 1 HS
  • ◆ 037 906 258 AM = Part No. of the control unit (for latest control unit version see parts catalogue)
  • ‒ Checking control unit coding:

Coding

For vehicles with

1

Manual gearbox

2

Automatic gearbox

Note:

Correct control unit number details and coding are only given at idling speed.

If the coding differs from the vehicle version, then:

  • ‒ Carry out electrical check, test steps 7 and 8
    , if necessary locate open circuit according to current flow diagram and rectify.
  • ‒ Press ⇒ button.
 
→ Indicated on display:
Rapid data transmission     HELP
Select function XX
  • ‒ Further measures see repair procedures.

Interrogating fault memory > < Technical data of self diagnosis