SEAT Workshop Service and Repair Manuals > Leon Mk2 > Power unit | 4LV Injection and Ignition System | Mixture preparation system, electronic inj.,Gas | Supplementary signals: testing | Signals from the brake light and brake pedal switches: testing

Test process

–	Connect the -V.A.G. 1551- (-V.A.G. 1552-). Switch on the ignition 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, 6 and 6 for “Display group number 66” 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)

–	Watch the value in field 2: (3rd and 4th digits to the left) Target value: 0 0 0 0

–	Depress the brake pedal all the way and watch the value in field 2: Target value: 0 0 1 1 Meaning of the numbers → Anchor

–

Press →.

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

–	Switch off the ignition.

If the target value is not reached:

–	Remove the lining from under the steering column: → Bodywork - Assembly work, interior; Rep. Gr.68

–	Disconnect the connector from the brake light/brake pedal switch.

–	To measure the resistance, connect the multimeter between switch contacts 1 and 4. Target value: ∞ Ω (no flow)

–	Depress the brake pedal. Target value: 0.0 Ω approx.

Read measured value block      66      →

–	To measure the resistance, connect the multimeter between switch contacts 2 and 3. Target value: 0.0 Ω approx.

–	Depress the brake pedal. Target value: ∞ Ω (no flow)

If the target value are not reached:

–	Replace the brake pedal switch.

If the target values are reached:

–	Connect the multimeter to test the voltage between contact 1 and earth. Target value: 11.5 V minimum.

–	Switch on the ignition.

–	To measure the voltage, connect the multimeter between contact 2 and earth. Target value: 11.5 V minimum.

If the target value is reached:

–	With the wiring diagram, test the wiring between 4-contacts connector contact 1 and fuse 15 for open circuits. Wiring resistance: 1.5 Ω max.

–	With the wiring diagram, test the wiring between 4-contacts connector contact 2 and fuse 24 for open circuits. Wiring resistance: 1.5 Ω max.

If the target value is reached:

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

–	Test for open circuits in the wiring between the test box and the 2-contacts connector (connector to the control unit) following the wiring diagram: Contact 3 + female contact 55 Contact 4 + female contact 56 Wire resistance: max. 1.5 Ω

–	Also test all the wiring for short circuits between wires.

–	Also test the wiring for short circuits to positive, battery and earth.

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