Checking sequence

WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 2002 Volkswagen Cabrio, 2001 Volkswagen Cabrio, 2000 Volkswagen Cabrio, 1999 Volkswagen Jetta, and 1999 Volkswagen Golf. However, it is still accessible from the selected car via links, so may be relevant.

Switch ignition OFF.
Connect VAG1598/18 test box to ECM wiring harness connector.

Fig 1: Connecting VAG1598/18 Test Box To ECM Wiring Harness Connector
Courtesy of VOLKSWAGEN OF AMERICA, INC.
Disconnect pressure line from pneumatic valve.
Switch ignition ON.
Bridge test box sockets 01 and 06 using jumper wires from VW1594 adaptor kit.
Connect test box terminals 49 to Ground using jumper wires from VW1594 adaptor kit.

Pump motor must run and air must exit the pressure line.

If pump motor runs, but no air exits hose:

Check pressure line, and if necessary replace pump motor.

If pump motor does not run:

Disconnect pump motor harness connector.
Connect VAG1527B LED tester to disconnected connector using jumper wires from VW1594 adaptor kit.

LED tester must light up.

If tester lights up (voltage supply OK):

Replace pump motor.

If tester does NOT light up:

Check wiring between test box socket 49 and pump relay using wiring diagram.
Check activation of relay and wiring to pump motor using wiring diagram.
Reconnect 2-pin harness connector.
Check DTC memory, then erase. See appropriate On Board Diagnostic (OBD) article.