Volkswagen Workshop Service and Repair Manuals

Checking function and voltage supply Test prerequisites l  Battery voltage at least 11.5 V l  Fuse for Fuel pump control unit -J538- OK. l  Fuel pump control unit -J538- OK. Test sequence:   Note Function of fuel pump is checked using final control diagnosis.

–  Connect vehicle diagnosis tester as follows: –  Push diagnosis cable connector onto diagnosis connection in driver footwell. –  Switch on ignition. –  Press buttons on display one after the other for Vehicle self-diagnosis, Engine electronics and Final control diagnosis. –  Press right arrow button ► on display up to final control diagnosis for fuel pump electronics. The fuel pump must now run slowly up to maximum speed.   Note The fuel pump runs very quietly. –  Switch off ignition. If fuel pump does not run: –  Remove bench seat → General body repairs, interior; Rep. gr.72.

–  Pull connector off fuel pump control unit -J538-.

–  Check voltage supply between contacts -1- and -6- using multimeter -V.A.G 1715-. l  Specification: approx. battery voltage Voltage supply not OK: –  Locate and eliminate open circuit referring to current flow diagram → Current flow diagrams, Electrical fault finding and Fitting locations. Voltage supply OK:

–  Remove cover -1- with fuel pump control unit -J538--2- from fuel delivery unit.

–  First check that the connector -arrow- is fitted securely by pulling the connector without pressing the catch. If connector was not inserted correctly, repeat functional check of fuel pump. –  Now pull off connector. –  Check the contacts on the connector and on the fuel delivery unit for damage.   WARNING Fuel supply line is pressurised. Wear eye protection and protective clothing to avoid possible injury and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Pull fuel lines -1- and -2- off flange.   Note t  Press in securing ring to release fuel lines. t  On vehicles with auxiliary heater the connector and the fuel line of the metering pump -V54- must also be separated.

–  Open locking ring using wrench -T10202-. –  Check that electrical wires between flange and fuel pump are connected. If no open circuit can be found: –  Fuel pump defective, renew fuel delivery unit → Chapter.