Checking The Input Signals
Checking The Input Signals
Test point 1
Tiptronic
- Ignition on
PST2 display:
Depends on the selector lever position: P, R, N, D
- Engine idling
- Brake pedal actuated
- Selector lever position P, R, N, D, M
PST2 display:
Depends on the selector lever position: P, R, N, D 1, D 2/ M 1, M 2
- Drive vehicle
PST2 display:
Depends on the selector lever position: P, R, N, D 1-5/ M 1-5
See "Actual values", Test point 1. Checking Actual Values
Test point 2
Signal, terminal 61
- Ignition on
- Engine off
PST2 display: not present
- Engine idling
PST2 display: present
- Engine idling
- Measure voltage between both poles on the battery
Voltmeter display: > 13 V
Check generator in the case of deviations
- Switch off ignition
- Pull off plug II on the instrument cluster
- Switch ignition on
- Measure the voltage on the instrument cluster plug II, pin 23 and ground
Voltmeter display: 0 V
- Engine idling
- Measure the voltage on the instrument cluster plug II, pin 23 and ground
Voltmeter display: > 13 V
- Switch off ignition
- Disconnect plug on generator (terminal 61)
- Switch ignition on
- Measure the voltage on the instrument cluster plug II, pin 23 and ground
Voltmeter display: 0 V
- Switch off ignition
- Ohmmeter on instrument cluster plug II pin 23 and ground
Ohmmeter display: Infinity ohm
- Ohmmeter on instrument cluster plug II pin 23 and plug on generator (terminal 61)
Ohmmeter display: < 5 ohm
Test point 3
Signal, terminal 15
- Ignition on
- Engine off
PST2 display: present
- Communication with the control module is not possible without terminal 15.
- Check fuse B 10
- See also Actual values, Test point 4. Checking Actual Values
Test point 4
Terminal 86s signal
- Ignition on
- Engine off
PST2 display: present
If not:
- Check fuse E1
- Switch off ignition
- Pull off plug III on the instrument cluster
- Switch on terminal 86S
- Measure the voltage between instrument cluster plug III, pin 1 and ground
Voltmeter display: Battery voltage
If battery voltage is present at plug III pin 1, replace the instrument cluster.
Test point 5
Terminal 58 signal (lighting)
- Ignition on
- Terminal 58 switched off
PST2 display: Off
- Terminal 58 switched on
PST2 display: On
If "Off" is displayed when terminal 58 is switched on:
- Switch off ignition
- Pull off plug II on the instrument cluster
- Terminal 58 switched on
- Measure the voltage between instrument cluster plug II pin 14 and ground
Voltmeter display: Battery voltage
Test point 6
Clock
- Ignition on
- Clock button not actuated
PST2 display: not actuated
- Clock button pressed
PST2 display: actuated
- Clock button turned to left
PST2 display: -actuated
- Clock button turned to right
PST2 display: +actuated
If the tester displays no signal, the instrument cluster is faulty.
Test point 7
Brake pad
- Ignition on
- Engine off
PST2 display: OK
If not:
- Check brake pads on all four brake discs for wear
- Switch off ignition
- Pull off plug I on the instrument cluster
- Pull off plug III on the instrument cluster
- Ohmmeter on instrument cluster plug III pin 13 and ground
Ohmmeter display: infinity ohms
- Ohmmeter on instrument cluster plug I pin 23 and plug III pin 13
Ohmmeter display: < 5 ohm
Test point 8
Brake fluid level
- Ignition on
- Engine off
PST2 display: OK
If not:
- Check brake fluid level in brake fluid reservoir
- Switch off ignition
- Pull off plug II on the instrument cluster
- Pull off plug on brake fluid reservoir
- Ohmmeter on instrument cluster plug II pin 4 and plug on brake fluid reservoir
Ohmmeter display: < 5 ohm
- Ohmmeter on brake fluid reservoir plug pin 2 and ground
Ohmmeter display: < 5 ohm
- Ohmmeter on instrument cluster plug II pin 4 and ground, level switch not actuated
Ohmmeter display: Infinity ohm
- Ohmmeter on instrument cluster plug II pin 4 and ground, level switch actuated
Ohmmeter display: < 5 ohm
Test point 9
Coolant level
- Ignition on
- Engine off
PST2 display: OK
If not:
- Check coolant level in reservoir
- Switch oft ignition
- Pull off plug II on the instrument cluster
- Pull off plug on sensor for coolant level display
- Ohmmeter on instrument cluster plug II pin 5 and ground
Ohmmeter display: Infinity ohm
- Ohmmeter on instrument cluster plug II pin 5 and plug on reservoir pin 1
Ohmmeter display: < 5 ohm
- Ohmmeter on reservoir plug pin 2 and ground
Ohmmeter display: < 5 ohm
- See also Drive links "Coolant warning light" and "Coolant temperature". Drive Links
Test point 10
Oil pressure
- Ignition on
- Engine off
PST2 display: not present
- Engine idling
PST2 display: present
If oil pressure "not present" is displayed when the engine is running:
- Check oil level
- Switch off ignition
- Pull off plug II on the instrument cluster
- Ohmmeter on instrument cluster plug II pin 6 and ground
Ohmmeter display: < 5 ohm
- Disconnect plug on oil pressure switch
- Ohmmeter on instrument cluster plug II pin 6 and plug on oil pressure switch, pin 1
Ohmmeter display: < 5 ohm
- Push plug onto oil pressure switch
- Engine idling
- Ohmmeter on instrument cluster plug II pin 6 and ground
Ohmmeter display: infinity ohms
- Check oil pump
Test point 11
Seat belt
- Ignition on
- Seat belt on driver's side not fastened
PST2 display: not fastened
Seat belt on driver's side fastened
PST2 display: fastened
- Switch off ignition
- Pull off plug II on the instrument cluster
- Switch ignition on
- Measure the voltage between instrument cluster plug II and pin 24 and ground
Voltmeter display: 0 V
- Switch off ignition
- Seat belt on driver's side not fastened
- Ohmmeter on instrument cluster plug II pin 24 and ground
Ohmmeter display: < 5 ohm
- Seat belt on driver's side fastened
- Ohmmeter on instrument cluster plug II pin 24 and ground
Ohmmeter display: infinity ohms
- Disconnect plug connection X16 for LHD vehicles and X17 for RHD vehicles
- Ohmmeter on instrument cluster plug II pin 24 and plug connection X16 or X17 on sleeve side, pin B5
Ohmmeter display: < 5 ohm
Test point 12
Spoiler button
- Ignition on
- Spoiler button (switch for rear spoiler) not actuated
PST2 display: not actuated
- Spoiler button (switch for rear spoiler) "extend" actuated
PST2 display: extend actuated
- Spoiler button (switch for rear spoiler) "retract" actuated
PST2 display: retract actuated
- Switch off ignition
- Pull off plug II on the instrument cluster
- Pull plug off the spoiler button
- Switch ignition on
- Measure the voltage between instrument cluster plug II pin 11 and ground
Voltmeter display: 0 V
- Measure the voltage between instrument cluster plug II pin 10 and ground
Voltmeter display: 0 V
- Switch off ignition
- Spoiler button "extend" actuated
- Ohmmeter on instrument cluster plug II pin 11 and ground
Ohmmeter display: < 5 ohm
- Spoiler button "retract" actuated
- Ohmmeter on instrument cluster plug II pin 10 and ground
Ohmmeter display: < 5 ohm
- See also Drive links "Spoiler" and "Spoiler warning light". Drive Links
Test point 13
Spoiler status
- Ignition on
- Spoiler retracted
PST2 display: retracted
- Spoiler extended
PST2 display: extended
Spoiler in intermediate position
PST2 display: is unknown
- See also Drive links "Spoiler" and "Spoiler warning light". Drive Links
- Switch off ignition
- Pull off plug II on the instrument cluster
- Spoiler extended
- Ohmmeter on instrument cluster plug II pin 9 and ground
Ohmmeter display: < 5 ohm
- Spoiler retracted
- Ohmmeter on instrument cluster plug II pin 26 and ground
Ohmmeter display: < 5 ohm
- Pull plug off the spoiler drive
- Ohmmeter on instrument cluster plug II pin 9 and plug on spoiler drive pin 2
Ohmmeter display: < 5 ohm
- Ohmmeter on instrument cluster plug II pin 26 and plug on spoiler drive pin 4
Ohmmeter display: < 5 ohm
- Ohmmeter on spoiler drive plug pin 5 and ground
Ohmmeter display: < 5 ohm
If no faults are detected in the wire, replace the motor for the rear spoiler
Test point 14
Washer fluid level
- Ignition on
- Engine off
PST2 display: OK
- Check washer fluid level
- Switch off ignition
- Washer fluid level full
- Pull off plug on sensor for fluid level display
- Ohmmeter directly on sensor for fluid level display, pin 1 and pin 2
Ohmmeter display: < 5 ohm
If not, replace sensor for fluid level display.
- Ohmmeter on plug of sensor for fluid level display pin 2 and ground
- Ohmmeter display: < 5 ohm
- Pull off plug II on the instrument cluster
- Ohmmeter on instrument cluster plug II pin 26 and plug on sensor for fluid level display, pin 1
Ohmmeter display: < 5 ohm
- See also Drive Links, "Washer fluid warning light". Drive Links
Test point 15
Washer fluid level full
- Ignition on
- Vehicle not locked
PST2 display: not present
- Central locking button actuated
- Vehicle locked
PST2 display: present
- Read out fault memory in alarm system control module and eliminate faults present
If the central locking function is OK.
- Switch off ignition
- Pull oft plug II on the instrument cluster
- Lock vehicle
- Ohmmeter on plug II of instrument cluster, pin 8 and ground
Ohmmeter display: < 5 ohm
- Unlock vehicle
- Pull plug I off the alarm system control module
- Ohmmeter on instrument cluster plug II pin 8 and plug I on alarm system control module pin 30
Ohmmeter display: < 5 ohm
Test point 16
On-board computer
- Ignition on
- Operating lever not actuated
PST2 display: not actuated
- Move operating lever upwards
PST2 display: actuated upwards
- Move operating lever downwards
PST2 display: actuated downwards
- Push operating lever forwards
PST2 display: actuated forwards
- Pull operating lever towards steering wheel
PST2 display: actuated backwards
- Switch off ignition
- Pull off plug on operating lever for on-board computer
- Ohmmeter on operating lever plug pin 1 and ground
Ohmmeter display: < 5 ohm
- Pull off plug II on the instrument cluster
- Ohmmeter on instrument cluster plug II pin 25 and plug on operating lever for on-board computer pin 5
Ohmmeter display: < 5 ohm
- Ohmmeter on instrument cluster plug II pin 22 and plug on operating lever for on-board computer pin 4
Ohmmeter display: < 5 ohm
- Ohmmeter on instrument cluster plug II pin 20 and plug on operating lever for on-board computer pin 2
Ohmmeter display: < 5 ohm
- Ohmmeter on instrument cluster plug II pin 21 and plug on operating lever for on-board computer pin 3
Ohmmeter display: < 5 ohm
Test point 17
Dimming
- Ignition on
- Dimming button not actuated
PST2 display: not actuated
- Dimming button actuated towards left
PST2 display: -actuated
- Dimming button actuated towards right
PST2 display: +actuated
- See also Actual values, Test point 5 Checking Actual Values and Drive links "Lamp dimming", "Gear display dimming", "Display dimming", "External dimming". Drive Links
Test point 18
Trip mileage
- Ignition on
- Kilometer button not actuated
PST2 display: not actuated
- Kilometer button actuated
PST2 display: actuated