Fuel Injectors, Checking

Fuel Injectors, Checking


A - Electrical testing of fuel injectors
- Disconnect harness connector from injector to be tested.







- Connect hand-held multi meter to fuel injector (resistance measurement range).
Specification: 13.5 - 15.5 Ohms


NOTE: When the engine is at operating temperature the electrical resistance of the injectors will be about 4 - 6 Ohms higher.


If the specification is not obtained:
- Replace fuel injector. Also observe notes on. Refer to "Fuel Injection Volume, Fuel Injector Leakage and Spray Pattern of Injectors, Checking" Testing and Inspection

B - Checking voltage supply

Test conditions
- Fuse for injectors OK
- Disconnect harness connector from fuel injector to be tested.







- Connect diode test lamp (for measuring voltage) between Ground (GND) and socket I of connector.
- Switch ignition on. The diode test lamp should light up.
- If diode test lamp does not light up, test for open circuits in wiring between contact 1 and fuse for injectors. If necessary, rectify open circuit.
- If diode test lamp lights up, test activation of injectors.

C - Testing activation of injectors
- Remove plug connector from the injector which is to be tested.







- Connect diode test lamp VAG1527 between the battery positive terminal (+) and contact 2 on the connector.
- Operate starter for a few seconds (the engine can be allowed to start).
Specification: the diode test lamp should start flashing.


NOTE: Diode test lamps with a low current draw continue to glow faintly between impulses from the engine control unit (rather than going out completely) and become much brighter when receiving an impulse.


If the diode test lamp does not flash:
- Connect test box VAG1598/31 to wiring harness for engine control unit. Do not connect to the engine control unit itself. Connecting VAG 1598/31 Test Box







- Test for open circuit or short to B+ in wiring between engine control module and contact 2 on harness connector for fuel injector being tested.

Contact 2 on connector Test box VAG
for injector, Cylinder No. 1598/31, socket
1 96
2 112
3 88
4 97
5 113
6 89

- Rectify short circuit or open circuit if necessary.
- If wiring is OK, replace Engine Control Module (ECM).