SEAT Workshop Service and Repair Manuals

Checking fuel pump control unit -J538-

Check the tool and equipment equivalence table according to the applicability between Seat / VW / Audi / Skoda → Chapter

Special tools and workshop equipment required

t	Manual multimeter -VAG 1526E-, see equivalent → Anchor

t	Auxiliary cable kit -VAG 1594C-, see equivalent → Anchor

t	Engine unit tester -VAG 1598/39-, see equivalent → Anchor

t	Test box (105) pins -VAG 1598/42-, see equivalent → Anchor

Test requirements l  Battery voltage at least 12.5 V.

l  Fuse in fuse holder -S228- (position 28) OK. l  Ignition switched off Checking voltage supply for fuel pump (from fuel pump control unit -J538-) –  Remove the luggage compartment cover. –  If necessary, fold forward right backrest of rear seat bench.

–  Loosen the bolts -arrows- and remove the fuel delivery unit.

–  Press back the protective sleeve. –  Connect the hand-held multimeter -VAG 1526E- with measurement needles and connectable adapters from theauxiliary measurement kit -VAG 1594C- between sockets -1- and -4-, as shown in the illustration. The connector remains connected.   Note The connector contacts are numbered accordingly on the rear of the connector. –  Start the engine. l  Specified value on starting and when idling: 4 ... 5.7 V. –  Actuate the gas pedal in jerks and release again (short gas supply). l  Specification: The voltage reading should rise at first, then fall and finally increase to the previous reading. If the display readout does not appear as described: –  Check the supply voltage and the excitation of the control unit for fuel pumps -J538-.

Fuel pump control unit -J538- : check supply voltage –  Remove the connector -arrow- from the fuel pump control unit -J538-.

–  Connect multimeter between contacts -3- and -4- of connector to measure voltage. –  Switch on the ignition. l  Specification: approx. battery voltage If specification is not obtained: –  Use current flow diagram to eliminate open circuit in wiring.

Fuel pump control unit -J538-: Checking activation –  To check voltage, connect the multimeter with measurement needles and connectable adapters from theauxiliary measurement kit -VAG 1594C- between sockets -4- and -5-, as shown in the illustration. The connector remains connected.   Note The connector contacts are numbered accordingly on the rear of the connector. –  Start the engine. l  Specified value when starting and when idling: Approx. 5.0 Volt. –  Actuate the gas pedal in jerks and release again (short gas supply). l  Specification: The voltage reading should rise at first, then fall and finally increase to the previous reading.

If the display readout does not appear as described: –  Switch ignition OFF. –  Connect the test box (105) pins -VAG 1598/42- to the wiring harness with adapter lead -VAG 1598/39 1- or adapter lead -VAG 1598/39 2-. The engine control unit is not connected. Connect earth clip of test box to negative terminal of battery.   Caution To avoid damaging electronic components, select the appropriate measuring range before connecting the test leads and observe the test conditions.

–  Check for breaks, shorts to earth or battery positive in the following wiring connection:

Connector Contact	Test box with (105) pins -VAG 1598/42- , socket
-5-	B 27

–  Repair the cable break or short-circuit according to the circuit diagram. If no fault is found: –  Replace the fuel pump control unit -J538-.