Testing Diesel direct injection system voltage supply: Audi (1Z)

With the ignition switched on the injection system receives its voltage supply via excess voltage protection relay -J249.

Test requirement:

Battery voltage not less than 12 V

Testing voltage supply

With the ignition switched off, connect test box V.A.G 1598 A to connector for engine control unit but not to the control unit itself (control unit remains disconnected) using adapter V.A.G 1598/5=>Page
23-46
.
Switch on ignition.

Connect voltage tester V.A.G 1527 B as follows using test leads from V.A.G 1594 A:

Test box V.A.G 1598 A / Socket No. · Specification
15 + earth · approx. battery voltage
16 + earth · approx. battery voltage
17 + earth · approx. battery voltage

If the specifications are not obtained:

Test excess voltage protection relay -J249 in front auxiliary relay carrier (relay position 14) under dash panel=>Page
23-90
, and also check the wiring.

=> Current flow diagrams, Electrical fault-finding and Fitting locations

Testing earth connection for control unit

Connect voltage tester V.A.G 1527 B as follows using test leads from V.A.G 1594 A:

Test box V.A.G 1598 A / Socket No. · Specification
18 + battery positive · approx. battery voltage
19 + battery positive · approx. battery voltage

If the specifications are not obtained:

Check wiring.

=> Current flow diagrams, Electrical fault-finding and Fitting locations

Testing excess voltage protection relay -J249

Note:

Excess voltage protection relay -J249 is in the front auxiliary relay carrier (relay position 14) under the dash panel.

Remove storage compartment (shelf) on driver's side.

=> General body repairs; Repair group 70; Dash panel; Removing driver's side shelf
General body repairs
Dash panel
Removing driver's side shelf

Switch on ignition.
Excess voltage protection relay -J249 should "pull" (i.e. click).

Note:

The clicking of the valve is difficult to hear and is therefore best checked by touching the relay.

If the relay clicks but there is no voltage at the control unit:

Test wiring between excess voltage protection relay -J249 and control unit.

=> Current flow diagrams, Electrical fault-finding and Fitting locations

If the relay does not click:

Test voltage supply to excess voltage protection relay -J249.

Testing voltage supply to excess voltage protection relay -J249

Switch off ignition.
Remove relay from position 14 on front auxiliary relay carrier under dash panel.
Switch on ignition.
Connect voltage tester V.A.G 1527 B to the following contacts in relay position 14 on relay panel:

Position 14 in front / auxiliary relay carrier / Contact No. · Specification
6 + earth · approx. battery voltage
8 + earth · approx. battery voltage
2 + battery positive · approx. battery voltage

If all the readouts match the specifications but there is still no voltage input at terminal 15 of the control unit (=>Testing voltage supply, Page
23-87
), renew excess voltage protection relay -J249.

If the specifications are not obtained:

Check the wiring.

=> Current flow diagrams, Electrical fault-finding and Fitting locations