Brake Light Switch: Testing and Inspection

Brake Light Switch -F And Brake Pedal Switch -F47, Checking

- Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAS 5051/ VAG 1551 Scan Tool" under "Powertrain Management/Computers and Control Systems/Testing and Inspection" Testing and Inspection

When doing this the ignition must be switched on.

Indicated on display


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display


Read Measuring Value Block
Input display group number XXX


- Press buttons -0-, -6- and -6- to select "display group number 066" and confirm entry with -Q- button.

Indicated on display


Read Measuring Value Block 66 ->
1 2 3 4


- Observe brake light/brake pedal switch in display field 2.

Display Group 066:

If display does not appear as described:

Check switch
- Remove storage compartment on driver's side.
- Disconnect harness connector on brake light/brake pedal switch.
- Connect hand-held multimeter for resistance measurement between terminals 1 and 2.


NOTE: The connector slots are marked on the back side of the connector.


- Specification: Infinity Ohms (no continuity)

- Depress brake pedal.
- Specification: approx.: 0 Ohms

- Connect hand-held multimeter for resistance measurement between terminals 3 and 4.
- Specification: approx.: 0 Ohms

- Depress brake pedal.
- Specification: Infinity Ohms (no continuity).

If specifications are not obtained:
- Check adjustment or replace brake light/brake pedal switch.

If specifications are not met:

Check voltage supply
- Connect VAG1527 B between following sockets on harness connector:

Harness connector Measure against
terminal
1 Ground (GND)

- The LED must come on

Harness connector Measure against
terminal
3 Ground (GND)

- Switch ignition on.
- The LED must come on

If LED does not come on:
- Check wiring connection from terminal 1 or 3 of connector for open circuit (fuse) or short circuit to Ground (GND).
- If necessary eliminate open circuit or short circuit to Ground (GND)

If LED comes on:

Check activation
- Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to the engine control module itself. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" under "Powertrain Management/Computers and Control Systems/Testing and Inspection" Testing and Inspection

Test the following wiring connections for open circuits and short to B+ or Ground (GND):

Harness connector VAG1598/31 test box,
terminal socket
2 56
4 55

- Repair any open/short circuit as necessary.