Wire and Component Test Using VAG1598/31 Test Box

Electrical Test Using VAG1598/31 Test Box


NOTE: VAG1598/31 test box is designed so that it can be simultaneously connected to the wiring harness at the Engine Control Module (ECM) and also to the ECM itself.

This is advantageous because electronic engine control remains fully functional (e.g. measurement of signals with engine running) when the test box is attached.

Relevant test procedures note whether Engine Control Module (ECM) should also be connected to the test box or not.

Use the following for the test: hand held multimeter (Fluke 83 or equivalent) or the VAG1715 voltage tester and the VAG1527 diode test lamp.

Always use adapter cables from VAG1594 connector test kit for connecting special tools to the VAG1598/31 test box.

Perform adaptation of Engine Control Module (ECM) to throttle valve control module after reconnecting the Engine Control Module (ECM), refer to Powertrain Management - Computers and Control Systems - Engine Control Module - Service and Repair - Procedures


CAUTION! To reduce the risk of damage to electronic components, switch on component to be tested before connecting test wires and observe test requirements.


- Switch ignition off.
- Remove cover of protective housing for control modules.






- Using a screwdriver, carefully pry off retaining bracket (arrow).
- Then disengage connector from control module and disconnect.






- Connect VAG1598/31 test box to connector of wiring harness. Ground (GND) clip at test box (not visible in illustration) must be clipped to battery minus. Relevant test procedures note whether Engine Control Module (ECM) should also be connected to the test box.
- Perform test as described in relevant repair sequence.

- Disconnect harness connector at cruise control switch.

Wire connection must be checked for short circuit to B+, Ground (GND) and for open circuit

- Check wire connection according to wiring diagram.
- Repair open circuit or short circuit if necessary.

Cruise control switch must be replaced if wire connection is OK.