With Manufacturer's Scan Tool

Brake Light Switch and Brake Pedal Switch Signal, Checking

Special tools and equipment
- VAG1551 Scan Tool (ST) or VAG1552 mobile scan tool with VAG1551/3 adapter cable
- VAG1598/31 test box
- Multimeter (Fluke 83 or equivalent)
- VW1594 adapter set
- Wiring diagram

Test requirements







- Fuses 5, 10, 13 and 29 OK
- Battery voltage at least 11.5 V

Test sequence
- Connect VAG1551 (VAG1552) Scan Tool (ST).
- Switch ignition on and press buttons -0- and -1- to insert "Engine Electronics" 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 and 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 input display group number 66 (066) and press -Q- button to confirm input.

Indicated on display: (1-4 = display fields)


Read Measuring Value Block 66 ->
1 2 3 4


- Observe display in display field 2 (3rd and 4th positions from left):
Specified value: x x 0 0
- Depress brake pedal and observe display in display field 2.
Specified value: x x 11
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.

If the display does not change:
- Disconnect 4-pin harness connector from brake light switch and brake pedal switch.
- Measure resistance between terminals -1- + -4- of switch.
Specified value with brake pedal not depressed: Infinity ohms
Specified value with brake pedal depressed: max. 1.5 ohms







- Measure resistance between terminals -2- + -3- of switch.
Specified value with brake pedal not depressed: 1.5 ohms
Specified value with brake pedal depressed: max. Infinity ohms

If the specified values are not obtained:
- Replace brake light switch -F- and brake pedal switch -F47-.
- Check DTC memory. If necessary, repair any malfunctions and erase DTC memory.
- Display readiness code.

If DTC memory has been erased or the Engine Control Module (ECM) was disconnected from permanent battery (B+) voltage, the readiness code must be generated again. Monitors, Trips, Drive Cycles and Readiness Codes

If the specified values are obtained:





- Connect multimeter to measure voltage between terminal -1- and Ground (GND).
Specified value: at least 11.5 V
- Connect multimeter to measure voltage between terminal -2- and Ground (GND).
- Switch ignition on.
Specified value: at least 11.5 V

If the specified values are not obtained:
- Check wiring between 4-pin harness connector terminals 1 and 2 to central electric using wiring diagram.

If the specified values are obtained:
- Remove wiper arms and plenum chamber cover.





- Connect VAG1598/31 test box to Engine Control Module (ECM) wiring harness. Engine Control Module (ECM) is not connected by this action.





- Check wiring between test box and 4-pin harness connector for open circuit according to wiring diagram.
- Terminal -3- + socket 55
- Terminal -4- + socket 56
Wire resistance: max. 1.5 ohms

- Additionally, check wires for short to one another.
- Additionally, check wiring for short to battery positive (B+) or Ground (GND).