Scan Tool Connecting

Wiring And Component Check With Test Box V.A.G 1598/31

NOTE:







- The test box V.A.G. 1598 / 31 is designed so it can be simultaneously connected to the control module wiring harness and to the control module itself.
- This has the advantage of enabling the engine management system to remain fully operational even with the test box connected (for example, when testing signals while the engine is running).
- The instructions for performing the individual tests indicate whether or not the engine control module itself also needs to be connected to the test box.
- Use the multimeter V.A.G 1526, Fluke 83 or the multimeter V.A.G 1715 and the diode test lamp V.A.G 1527 for the checks.
- To connect the testers to test box 1598/31, always use the adapter leads from adapter set V.A.G 1594.

WARNING: To prevent damage to the electronic components, switch to the respective measuring range before connecting the measuring cable and observe the test requirements.

Connecting test box V.A.G 1598/31
- Switch off ignition.







- Remove rubber seal from plenum chamber in direction of arrow.
- Remove plenum chamber cover -1- from front.







- Remove cover for electronics box in plenum chamber (arrows).







- Carefully proof retainer bar with a screwdriver (arrow).







As a deterrent against unauthorized access to the connectors on the engine control module, the control module -1- is bolted to a metal casing - 4- by means of shear bolts -3- and a locking plate -2-.

The threads of the shear bolts are additionally coated with a thread-locking compound to make them more difficult to remove.

In order to disconnect the connectors from the engine control module (for instance when connecting the test box or replacing the control module), the control module must be separated from the protective casing. The required procedure is described below:

Required tools







- Hot-air blower -1- (from wiring repair set VAS 1978)
- Nozzle attachment -2- (also included in wiring repair set VAS 1978)
- A normal (commercially available) vise-grip wrench

Work sequence

CAUTION: Keep exactly to the following procedure to avoid damage (burning) to the wiring, connectors, insulation or the control modules. Follow the operating instructions supplied with the hot-air blower.







- Pivot engine control module with protective casing toward engine compartment so that locking plate (Item -2- in illustration) is visible. Place a clean cloth under engine control module with protective casing.







- Set controls on hot-air blower as shown in illustration: temperature control -2- to maximum heat and two-stage air delivery switch -3- to setting 3.

NOTE: In the next step the blower is used to heat the threads for the shear bolts in the locking plate. This reduces the effect of the thread-locking compound so the bolts can then be removed more easily.


WARNING: When the threads in the locking plate are heated up, this also heats the shear bolts and parts of the metal casing. Take care not to burn your hands. Also make sure that, as far as possible, you only apply heat to the threads and not to the adjacent parts. Cover these up if necessary.







- Apply nozzle -1- of hot-air blower to thread in locking plate so that nozzle surrounds thread. Nozzle may rest against top of metal casing.
- Switch on blower and apply heat to thread for about 20 to 25 seconds.







- Apply vise-grip wrench -1- to bolt head -2- and unscrew shear bolt in direction indicated (arrows).
- Repeat procedure for second shear bolt. Be particularly careful here because control module connectors are very close to this bolt.







- Apply nozzle -1- of hot-air blower to second thread in locking plate so that nozzle surrounds thread. Nozzle may rest against top of metal casing.
- Switch on blower and apply heat to thread for about 20 to 25 seconds.







- Apply vise-grip wrench -1- to bolt head -2- and unscrew shear bolt in direction indicated (arrows).

The engine control module can now be separated from the metal casing.

- Release connectors on engine control module and disconnect.







- Connect test box V.A.G 1598/31 to connector on wiring harness. Also connect Ground clamp (arrow) to Ground. Instructions for individual tests indicate whether or not engine control module itself also needs to be connected to test box.
- Perform test as described in relevant repair instructions.

Installing engine control module
Installation is performed in the reverse sequence. The control module must be placed back into the protective casing (use new shear bolts).