With Manufacturer's Scan Tool
Speed Signal, Checking
Special tools and equipment
- Scan tool VAG 1551 or vehicle system tester V.A.G 1552 with cable VAG 1551/3B
- Test box V.A.G 1598/31
- Hand multimeter V.A.G 1526 or multimeter VAG 1715
- Adapter set V.A.G 1594
- Wiring diagram
Check conditions
- All Fuses must be OK
- The battery voltage must be at least 11.5 V
- Speedometer must be OK.
Test sequence
NOTE: To check the speed signal the vehicle must be driven. To do this a second person is necessary.
WARNING!
During a road test in an airbag-equipped vehicle, test equipment must always be fastened to and operated from the rear seat by a second technician.
- Connect scan tool VAG 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control module. Engine must be running at idle speed.
Connecting scan tool and selecting Engine Control Module (ECM). Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/VAG1551 Scan Tool" Testing and Inspection
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
Input display group number XXX
- Press buttons 0, 0 and 5 for "Display group number 5" and confirm entry with Q button.
Indicated on display (1-4 = Display zones)
Read Measuring Value Block 5 ->
1 2 3 4
- Perform test drive with a 2nd person to observe display.
Observe the valid safety precautions when carrying out a road test.
- Observe figure displayed in display zone 3:
Specification: approx. driven speed
- Press -> button.
- Press buttons 0 and 6 for the "End output" function and confirm input with Q button.
- Switch ignition off.
If no speed is displayed:
- Remove inner plenum chamber cover, left:
- Connect test box V.A.G 1598/31 to control module wiring harness. Engine control module is not connected by this action.
- Connect multimeter to measure voltage between test box sockets 2 + 20.
- Switch ignition on.
- Lift vehicle at front left.
- Rotate front wheel and observe voltage display.
Specification: between 0 and at least 4 Volt fluctuating
NOTE: If necessary, hold the front right wheel to prevent it from turning.
If the display does not fluctuate:
- Check wiring to speedometer/speedometer sensor.
- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory. Refer to "Displaying and Reading Trouble Codes/With Manufacturers Scan Tool/DTC Memory Checking and Erasing" Testing and Inspection
- Check drivetrain CAN-Bus:
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again.
Refer to "Monitors, Trips and/or Drive Cycle/Readiness Code, Displaying" Testing and Inspection
Refer to "Monitors, Trips and/or Drive Cycle/Readiness Code, Generating" Testing and Inspection