Brake Light Switch and Brake Pedal Switch Signal, Checking

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.

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).