SEAT Workshop Service and Repair Manuals > Leon Mk1 > Power unit | 4LV Injection and Ignition System | Mixture preparation system, electronic inj.,Gas | Supplementary signals: testing | Speed signal: testing

Test process

Note!

To test the speed signal the vehicle must be moving. To do so another person is required.

Caution

Secure the fault reader in the rear seat and operate it from there.

Take the necessary precautions when doing road test → Chapter.

–	Connect the -V.A.G. 1551- (-V.A.G. 1552-). Start the engine and enter the “address code” 01 to select the engine control unit. (Fault reader: connecting and selecting the engine control unit → Chapter.)

Reading on display:

–	Press 0 and 8 for the function “Read measured value block” and confirm the entry with the Q key.

Rapid data transmission             HELP

Select function XX

Reading on display:

–	Press 0, 0 and 5 for “Display group number 5” and confirm the entry with the Q key.

Read measured value block           HELP

Enter display group no. XXX

Reading on display: (1...4 = display fields)

–	Do a road test with a second person to watch the values shown on the display.

–	Watch the value displayed in the field 3: Target value: approx. running speed

–

Press →.

–	Press 0 and 6 for the function “End transmission” and confirm the entry with the Q key.

–	Switch off the ignition.

If no speed is displayed:

Read measured value block      5      →

–	Connect test box -V.A.G. 1598/31- to the wiring harness of the control unit, without connecting the engine control unit.

–	To test the voltage, connect the multimeter between female contacts 4 (terminal 15) + 54 (speed signal) of the test box.

–	Switch on the ignition.

–	Raise the vehicle at the front left.

–	Turn the front left wheel by hand watching the voltage display. Target value: oscillates between 1 and at least 4 volts

Note!

When doing so, the front right wheel should not turn; if necessary, block it.

If the value shown does not oscillate:

–	Test the wiring to the speedometer or to the speedometer sender: → Current flow diagrams, Electrical fault finding and Fitting locations

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