Brake Light Switch: Testing and Inspection
Brake Light Switch -F- And Brake Pedal Switch -F47-, Checking
- Connect vehicle diagnostic, testing and information system VAS 5051 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", 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 66:
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.
- Specified value: infinity Ohms (no continuity)
- Depress brake pedal.
- Specified value: approx.: 0 Ohm
- Connect hand-held multimeter for resistance measurement between terminals 3 and 4.
- Specified value: approx.: 0 Ohm
- Depress brake pedal.
- Specified value: 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 Measures against
Terminal
1 Ground (GND)
- The LED must come on
Harness connector Measures 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/Wiring And Component Check With VAG1598/31 Test Box", Testing and Inspection
Test the following wiring connections for open circuits and short to B+ or Ground (GND):
Harness connector VAG1598/31 test
Terminal box, socket
2 56
4 55
- Repair any open/short circuit as necessary.