Engine Speed Signal (RPM), Checking

Engine Speed Signal (RPM), 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
- Speedometer must be OK., checking speedometer
- Selector lever must be in position "P" or "N" on vehicles with an automatic transmission

Test sequence


NOTE: To check the speed signal the vehicle must be driven and 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 VAG 1551 scan tool ((VAG 1552). Start engine and select "Address word" 01 of Motronic Engine Control Module (ECM) -J220-. Engine must be running at idle speed. 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
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 to 4 = Display zones)


Read measuring value block 5 ->
1 2 3 4


- Test drive vehicle 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 "End output" function and confirm input with -Q- button.
- Switch off ignition.

Continuation

If no speed is displayed:
- 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.
- Connect multimeter to measure voltage between test box sockets 3 (terminal 15) + 54 (speed signal).
- Switch on ignition.
- 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, 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