With Manufacturer's Scan Tool
Signal From Brake Light Switch -F- And Brake Vacuum Vent Valve Switch -F47-, Checking
Special tools, test equipment and auxiliary items
- VAG 1551 scan tool or VAG 1552 mobile scan tool with VAG 1551/3B cable
- VAG 1598/31 test box
- VAG 1526 hand multimeter or VAG 1715 multimeter
- VAG 1594 adapter set
- Electrical Wiring Diagram
Test conditions
- All fuses must be OK
- Battery voltage must be at least 11.5 V
- Brake lights functioning OK
- All electrical accessories, e.g. lights and rear window defroster must be switched off
- Selector lever must be in position "P" or "N" on vehicles with an automatic transmission
Test sequence
- Connect VAG 1551 scan tool ((VAG 1552). Switch ignition on and select Motronic Engine Control Module (ECM) -J220- with "Address word" 01. Connecting scan tool and selecting Motronic Engine Control Module (ECM) -J220-. [1][2][3]Connecting VAG 1551 Scan Tool
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- for function "Read measuring value block" and confirm entry with -Q- button.
Indicated on display
Read measuring value block HELP
Input display group number XXX
- Press buttons -0-, -6- and -6- for "display group 66" and confirm with -Q- button.
Indicated on display (1 to 4 = Display zones)
Read measuring value block 66 ->
1 2 3 4
- Observe display in display zone 2: (1st and 2nd positions from right) Brake pedal not depressed:
Specification: x x x x x x 0 0
- Depress brake pedal fully and observe display in display zone 2.
Specification: x x x x x x 1 1
- Press -> button.
- Press buttons -0- and -6- for "End output" function and confirm input with -Q- button.
- Switch off ignition.
If the display does not change:
- Remove driver's side footwell cover.
- Disconnect 4-pin connector from Brake Light Switch -F- and Brake Vacuum Vent Valve Switch -F47-.
- Measure resistance between terminals 1 + 4 of switch.
Specification:
- Brake pedal not depressed: Infinity Ohms (no continuity)
- Brake pedal depressed: Max. 1.5 Ohms
- Measure resistance between terminals 2 + 3 of the switch.
Specification: 0 Ohms
- 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 Vacuum Vent Valve Switch -F47-.
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory, Checking and Erasing DTC Memory. Reading Diagnostic Trouble Codes
- Read readiness code. If DTC memory has been erased or Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive, readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes
If the specifications are obtained:
- Connect multimeter to measure voltage between terminal 1 and Ground (GND).
Specification: at least 11.5 V
- Connect multimeter to measure voltage between terminal 2 and Ground (GND).
- Switch on ignition.
Specification: min. 11.5 V
If the specifications are not obtained:
- Check wiring between 4-pin connector terminals 1 and 2 to central electrics using Electrical Wiring Diagram.
If the specifications are obtained:
- Remove inner plenum chamber cover, left.
- Connect VAG 1598/31 test box to control module wiring harness. Motronic Engine Control Module (ECM) -J220- is not connected by this action.
- Check wiring for open circuit between test box and 4-pin connector using Electrical Wiring Diagram.
- terminal 3 + socket 55
- terminal 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 (GND).
If no wiring malfunction is found:
- Replace Motronic Engine Control Module (ECM) -J220-.