SEAT Workshop Service and Repair Manuals > Leon Mk2 > Power unit | 1AV Injection and Ignition System | Mixture preparation system, electronic inj.,Gas | Engine control unit

Control unit voltage supply: checking

Special tools and workshop equipment required

t	Hand multimeter -V.A.G 1526 A- or multimeter -V.A.G 1715-

t	Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with cable -V.A.G 1551/3B-

t	Auxiliary measuring set -V.A.G 1594 C-

t	Test box -V.A.G 1598/18-

t	Current flow diagram

Checking conditions

l	Battery voltage at least 11 V.

l	Alternator, OK.

Checking process

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

Indicated on the display:

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

Rapid data transfer                 HELP

Select function XX

Indicated on the display:

–	Press keys 0, 0 and 2 for “Display group number 2” and confirm entry with the Q key.

Read measured value block           HELP

Input display group number XXX

Indicated on the display:

(1…4 = display zones)

–	Read off figure displayed in display field 3.

Specification: approx battery voltage, constant.

–	Press the → key.

–	Press keys 0 and 6 for the “End output” function and confirm input with the Q key.

If the displayed value oscillates or does not reach battery voltage.

–	Switch ignition off.

Read measured value block 2           ->

         1         2         3         4

–	Connect test box -V.A.G 1598/18- to control unit wiring harness.

–	Measure supply voltage using multimeter and test cables from -V.A.G 1594 C- between sockets 1+21 of test box.

Specification: at least 11.5 V

–	Switch ignition on.

–	Measure supply voltage using multimeter and test cables from -V.A.G 1594 C- between sockets 1+23 of test box.

Specification: at least 11.5 V

If the specifications are not attained:

–	Check wiring connections to relay plate according to current flow diagram: → Current flow diagrams, Electrical fault finding and Fitting locations

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