With Manufacturer's Scan Tool
Signal From Brake Light Switch And Brake Pedal Switch, Checking
Special tools, test equipment and auxiliary items
- Scan tool V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3B
- Test box VAG 1598/31
- Multimeter (Fluke 83 or equivalent)
- Adapter set V.A.G 1594
- Wiring diagram
Test conditions
- Fuses 5, 10, 13 and 29 must be OK
- The battery voltage must be at least 11.5 V
- All electrical consumers, e.g. lights and rear window heating must be switched off
Test sequence
- Connect the scan tool V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control module with the "Address word" 01. Connecting scan tool and selecting Engine Control Module (ECM). Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/VAG 1551 Scan Tool", Testing and Inspection
Indicated on display
Rapid data transfer HELP
Select function XX
- Press keys 0 and 8 for the function "Read measuring value block" and confirm entry with Q key.
Indicated on display
Read measuring value block HELP
Input display group number XXX
- Press keys 0, 6 and 6 for "display group 66" and confirm with Q key.
Indicated on display (1-4 = Display zones)
Read measuring value block 66 ->
1 2 3 4
- Observe display in display zone 2: (3rd and 4th positions from left)
Specification: x x 0 0
- Depress brake pedal and observe display in display zone 2.
Specification: x x 1 1
- Press the -> key.
- Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
- Switch off ignition.
If the display does not change:
- Remove driver's storage compartment:
- Pull 4-pin connector off brake light switch and brake pedal switch.
- Measure resistance between contacts 1 + 4 of the switch. Specification:
Brake pedal not depressed: Infinity Ohms
Brake pedal depressed: Max. 1.5 Ohms (no continuity)
- Measure resistance between contacts 2 + 3 of the switch. Specification:
Brake pedal not depressed: Max. 1.5 Ohms
Brake pedal depressed: Infinity Ohms (no continuity)
If the specifications are not obtained:
- Replace brake light switch -F- and brake pedal switch -F47-.
- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory, checking and erasing DTC memory. Refer to "Displaying, Reading and Erasing Trouble Codes/With Manufacturers Scan Tool/DTC Memory, Checking And Erasing", Testing and Inspection
- Read-out the readiness code. If the DTC memory has been erased or the engine control module was disconnected from permanent positive, the readiness code must be generated again.
Refer to "Monitors Trips and/or Drive Cycle/Displaying Readiness Code", Testing and Inspection
Refer to "Monitors Trips and/or Drive Cycle/Generating Readiness Code", Testing and Inspection
If the specifications are obtained:
- Connect multimeter to measure voltage between contact 1 and Ground.
Specification: at least 11.5 V
- Connect multimeter to measure voltage between contact 2 and Ground.
- Switch on ignition.
Specification: min. 11.5 V
If the specifications are not obtained:
- Check wiring between 4-pin connector contacts 1 and 2 to central electrics using wiring diagram.
If the specifications are obtained:
- Remove inner plenum chamber cover, left:
- Connect test box V.A.G 1598/31 to control module wiring harness. The engine control module is not connected by this action.
- Check wiring for open circuit between test box and 4-pin connector for open circuit using wiring diagram.
Contact 3 + socket 55
Contact 4 + socket 56
Wire resistance: Max. 1.5 Ohms
- Also check wires for short to one another.
- Also check wiring for short to battery positive or Ground.
If no wiring problem is detected:
- Replace Engine Control Module (ECM)