SUPPORT GROUP 7N9591 - Caterpillar

Electrical shock hazard. The electronic unit injector system uses 90-120 volts.
Turn the key switch to the OFF position. A strong electrical shock hazard is present if the key switch is not turned off.
Disconnect the P2 ECM connector from the ECM. Connect a 140-2266 Cable (Seventy-Pin Breakout) to the ECM. Do not connect the engine harness to the breakout T.
Use a jumper wire to short between the socket of the suspect injector and the common socket of the suspect injector.
Turn the key switch to the ON position.
Perform the "Injector Solenoid Test" at least twice.Expected Result:Cat ET displays "Short" for the cylinder with the jumper wire.Note: When the engine harness is disconnected, all of the diagnostic codes for supply voltage to the sensors will be active. Clear all of these diagnostic codes after completing this test step.Results:
OK - The ECM is OK.Repair: If two injectors that share a common wire indicate "Open", inspect the common wire for problems. The open circuit is probably caused by an open in the common wire.Repair the engine harness or replace the engine harness, as required.Verify that the repair eliminates the problem.STOP
Not OK - There may be a problem with the ECM.Repair: Temporarily connect a test ECM.Remove the breakout T and reconnect the P2 ECM connector.Perform the "Injector Solenoid Test".If the test ECM fixes the problem, reconnect the suspect ECM.If the problem returns with the suspect ECM, replace the ECM.Verify that the repair eliminates the problem.STOPTest Step 8. Check the Harness between the ECM and the Valve Cover Base for a Short Circuit
Electrical shock hazard. The electronic unit injector system uses 90-120 volts.
Turn the key switch to the OFF position. A strong electrical shock hazard is present if the key switch is not turned off.
Disconnect the P300 injector harness connector from the valve cover base.
Turn the key switch to the ON position.
Perform the "Injector Solenoid Test" at least twice.Expected Result:All cylinders indicate "Open".Results:
OK - All cylinders indicate "Open".Repair: Reconnect the P300 injector harness connector. Proceed to Test Step 10.
Not OK - One or more cylinders indicate "Short". Note the cylinders that indicate "Short". Proceed to Test Step 9.Test Step 9. Check the ECM for a Short Circuit
Electrical shock hazard. The electronic unit injector system uses 90-120 volts.
Turn the key switch to the OFF position. A strong electrical shock hazard is present if the key switch is not turned off.
Disconnect the P2 ECM connector from the ECM and check for evidence of moisture entry.
Turn the key switch to the ON position.
Perform the "Injector Solenoid Test" at least twice.Expected Result:All cylinders indicate "Open" when the P2 ECM connector is disconnected from the ECM.Note: When the engine harness is disconnected, all of the diagnostic codes for supply voltage to the sensors will be active. Clear all of these diagnostic codes after completing this test step.Results:
OK - The short circuit is in the engine harness.Repair: The problem is most likely in the supply wire to the injector. Inspect the connectors for moisture and corrosion. Also, check the supply wire