With Manufacturer's Scan Tool

Signal From Brake Light Switch and Brake Pedal Switch, Checking

Special tools and equipment
- V.A.G 1551 Scan Tool (or VAG 1552 mobile scan tool) with VAG 1551/3 cable
- VAG 1598/31 test box
- VAG 1526 multimeter or VAG 1715 multimeter
- VAG 1594 connector test kit
- Wiring diagram

Test sequence
- Connect V.A.G 1551 scan tool (VAG 1552). Switch ignition on and select the Engine Control Module (ECM) using address word 01. Refer to Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting V.A.G 1551 Scan Tool [1][2][3]Connecting VAG 1551 Scan Tool

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press - Q- button to confirm input.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press buttons -0-, -6- and -6- to select "Display group number 66". Press -Q- button to confirm input.

Indicated on display

Read Measuring Value Block 66 ->
1 2 3 4

- Observe reading in display field 2. (3rd and 4th position from left)
Specification: x x 0 0

- Press brake pedal and observe reading in display field 2.
Specification: x x 11

- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06. Press -Q- button to confirm input.
- Switch ignition off.

If specified value is not obtained:
- Remove driver-side storage compartment:
- Disconnect harness connector at brake light switch and brake pedal switch.






- Connect multimeter between terminal 1 and 4 for resistance measurement.
Expected value: infinity Ohms (no flow of electricity)

- Press brake pedal.
Specification: approx. 0 Ohms

- Connect multimeter between terminals 2 and 3 to make resistance measurement.
Specification: approx. 0 Ohms

- Press brake pedal.
Expected value: infinity Ohms (no flow of electricity)

If specified values are not obtained:
- Replace brake light switch 1 brake pedal switch.

If specified values are obtained:






- Connect multimeter between terminal 1 and Ground (GND) to make voltage measurement.
Specification: at least 11.5 V

- Switch ignition on.

- Connect multimeter between terminal 2 and Ground (GND) to make voltage measurement.
Specification: at least 11.5 V

If specified values are not obtained:
- Check wire between 4-pin connector terminal 1 and main fuse (2) and central electronics according to wiring diagram.

If the specified value is met:






- Connect VAG 1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.






- Check for breaks in wire between test box and 4-way connector (see wiring diagram).
Terminal 2 + socket 56
Terminal 4 + socket 55
Wire resistance: max. 1.5 Ohms

- Check wires for shorts among one another.
- Also check wires for shorts to battery B+ or Ground (GND).