Brake Light Switch: Testing and Inspection
Brake Light Switch and Brake Pedal Switch Signal Check
Special tools and equipment
- V.A.G1551/1552 Scan Tool (ST) with VAG1551/3 adapter cable
- VAG1598/22 test box
- Multimeter (Fluke 83 or equivalent)
- VW1594 adapter set
- Wiring diagram
Test sequence
- Connect V.A.G1551 (VAG1552) Scan Tool (ST). Refer to "Scan Tool Testing/VAG1551/Functional Check" under "Powertrain Management/Computers and Control Systems/Testing and Inspection Testing and Inspection
- 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 1 1
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Turn off ignition.
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. Refer to "Displaying and Reading Trouble Codes/With Manufacturer Scan Tool/Check DTC Memory (Function 02)" under "Powertrain Management/Computers and Control Systems" Testing and Inspection
- Display readiness code. Refer to "Monitors, Trips and/or Drive Cycle/Displaying Readiness Code" under "Powertrain Management/Computers and Control Systems" Testing and Inspection
If DTC memory has been erased or the Engine Control Module (ECM) was disconnected from permanent battery (B+) voltage, generate the readiness code again. Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" under "Powertrain Management/Computers and Control Systems" Testing and Inspection
If the specified values are obtained:
- Remove wiper arms and plenum chamber cover.
- Connect VAG1598/22 test box to control module wiring harness.
- Check wiring between test box and 4-pin harness connector for open circuit according to wiring diagram.
- Terminal -3- + socket 48
- Terminal -4- + socket 47
Wire resistance: max. 1.5 ohms
If the specified value is obtained:
- Check wire between 4-pin harness connector terminals -1- + -2- and Fuel Pump (FP) relay -J17- for open circuit according to wiring diagram.
Wire resistance: max. 1.5 ohms