VAG 1551 Scan Tool, connecting/selecting function

WARNING: This page is about a different car, the 1995 Volkswagen Jetta III, 1995 Volkswagen GTI, and 1994 Volkswagen Jetta III. However, it is still accessible from the selected car via links, so may be relevant.

A 16-pin Data Link Connector (DLC) is used for access to the vehicle's On Board Diagnostic (OBD) systems using the VAG 1551 Scan Tool (ST).

Requirements

Battery Positive Voltage (B+) OK
Fuse no. 21 (S21) or no. 22 (S22) OK
Ground (GND) connections on engine and transmission OK (location: On the upper intake manifold support or lower part of intake manifold).

For access to the Data Link Connector (DLC):

Open front ashtray and remove if necessary.
Slide small cover to the left -arrow-.
With ignition switched OFF, connect VAG 1551/3 adapter harness between Data Link Connector (DLC) and VAG 1551 Scan Tool (ST).

Fig 1: Connecting VAG 1551/3 Adapter Harness Between Data Link Connector And VAG 1551 Scan Tool

Indicated on display

* Operating modes 1 and 2 are displayed alternately.

Fig 2: Identifying VAG 1551 Scan Tool - VAG On Board Diagnostic Help Display

Depending on function desired:

Switch ignition ON
or
Start engine.
- See Selectable functions .
NOTE:
- Additional operating instructions can be printed out by pressing the HELP button on the VAG 1551 Scan Tool (ST).
- The --> button advances the Scan Tool (ST) program sequence.
Operate VAG 1551 Scan Tool (ST) according to information and instructions on the display:
Press button -1- for Rapid data transfer operating mode.
Indicated on display

Fig 3: Identifying VAG 1551 Scan Tool - Rapid Data Transfer Help Display
Press buttons -0- and -1- (01 enters the address word for the vehicle system to be tested, BULL Engine Electronics BULL)
Indicated on display

Fig 4: Identifying VAG 1551 Scan Tool - Rapid Data Transfer (01 Engine Electronics)
Press -Q- button to confirm input.
Motronic Engine Control Module (ECM) identification will be displayed.

Fig 5: Identifying VAG 1551 Scan Tool - Coding 3 Display

For example:

021 906 258 BM =Part No. of Motronic Engine Control Module (latest version --> parts microfiche)
Coding 3 =Coding version

NOTE: Correct Motronic Engine Control Module (ECM) number and coding are displayed only with the engine running at idle speed (Closed Throttle Position).

Coding:

- Manual transmission without Exhaust Gas Recirculation (EGR)
- Automatic transmission without EGR
- Manual transmission with EGR
- Automatic transmission with EGR

Press button.

Indicated on display

Fig 6: Identifying VAG 1551 Scan Tool - Rapid Data Transfer Help Display