Fuel Injector Electrical Test

Using a backprobe set, connect Snap-On Personal Automotive Computer (PAC) tester to suspect fuel injector driver terminal. See IDENTIFYING FUEL INJECTOR DRIVER CONNECTOR TERMINALS (GEMS) or IDENTIFYING FUEL INJECTOR DRIVER CONNECTOR TERMINALS (BOSCH) table. Set Snap-On PAC tester to 100 volt scale and 5.0 mS. Start engine and allow it to idle. Compare fuel injector wave pattern with known-good wave pattern. See Fig 1.
If injector coil release spikes average approximately 80 volts, go to next step. An injector coil with a short will have average coil release spikes lower than 80 volts. Replace faulty fuel injector if coil release spikes average less than 80 volts.
Reset Snap-On PAC tester to 50 volt scale. Start engine and allow to idle. Check "On" time voltage for each injector. If "On" time voltage is constant at one volt or less, fuel injector drivers are operating properly. If "On" time voltage is not constant at one volt or less, go to next step.
If "On" time voltage is more than one volt, injector driver is not providing a consistent ground for the injector coil. Check for poor connections or loose wires between suspect fuel injector and ECM. See WIRING DIAGRAMS . Perform repairs as necessary. If no problems are found, substitute a known-good ECM and recheck for original symptom or indication. If symptom or indication goes away, replace original ECM.

IDENTIFYING FUEL INJECTOR DRIVER CONNECTOR TERMINALS (GEMS)

Fuel Injector Cylinder No.

⁽¹⁾ Connector Terminal No.

Wire Color

YEL/BLU

YEL/WHT

YEL/BLK

YEL/BRN

YEL/GRN

YEL/GRY

YEL/RED

YEL/PNK

⁽¹⁾	ECM Black 36-pin Connector. See Figure. See WIRING DIAGRAMS .

IDENTIFYING FUEL INJECTOR DRIVER CONNECTOR TERMINALS (BOSCH)