Purpose
To determine if fuel injectors are working (electronically) by energizing injectors in a programmed sequence. The ECM monitors the IDM results from this test and transmits DTCs, if injectors or injector circuits are not working correctly.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
Procedure
NOTE: The KOEO Injector Test can only be done with the EST using MasterDiagnostics® software.
1. Select Diagnostics from the menu bar.
2. Select Key-On Engine-Off Tests from the drop down menu.
NOTE: When using the EST to do KOEO or KOER
diagnostic tests, Standard Test is always selected
and run first. If the ignition switch is not cycled, the
Standard Test does not have to be run again.
3. From the KOEO Diagnostics menu, select Injector, then select Run to start the test.
NOTE: During this test, injector solenoids should click in a numerical sequence, not the firing order,
when actuated. If a series of clicks are not heard for each injector, one or more injectors are not activating.
The DTC window will show DTCs for electrical problems.
4. Record DTCs on Diagnostic Form. See “Diagnostic Trouble Codes” – Appendix C (page 643) for DTCs.
5. Correct problem causing active DTCs.
6. Clear DTCs.
7. When finished with this test, close the VIN+ session. Select Session from menu bar, then Close.
Possible Causes
• Injector wiring harness open or shorted
• Under Valve Cover (UVC) wiring
• Valve cover gasket
• Faulty wiring harness connection on injector coil
• Failed injector coil
• Failed Injector Drive Module (IDM)
• Failed ECM (not sending test request to IDM)
Hard Start and No Start Only
• Faulty wiring CAN2 datalink
• Faulty wiring IDM power and ground
• Faulty wiring IDM main power relay
