Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Data Link Connector: Testing and Inspection

Scan Tool VAG 1551 volatage supply checking

Data Link Connector Terminal Identification:





- Check for voltage supply at black Data Link connector A in vehicle
- observe polarity while performing this check:
Terminal 1 = Battery negative (-)
Terminal 2 = Battery positive (+)

If battery voltage is not obtained
- check wiring using wiring diagram, repair or replace as necessary

- switch Fluke 83 multimeter to resistance range
- connect multimeter to VAG 1551/1 adaptor cable and check for continuity