SHUTOFF GP-ELECTRICAL 7C0948 - Caterpillar

Electrical Shock Hazard. The unit injector system uses 90 - 120 volts. The ECM sends this signal to the unit injectors. Do not come in contact with the unit injector harness connector while the engine is operating. Failure to follow this instruction could resulting in personal injury or death.
Table 2
Troubleshooting Test Steps Values Results
1. Check for Active Codes and Logged Codes
A. Establish communication between Cat ET and the engine ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Determine if the -5 or -6 code is active or logged.
Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Codes
Result: A code is active or logged.
Proceed to Test Step 3.
Result: A code is not active or logged.
Proceed to Test Step 2.
2. Perform a "Cylinder Cutout Test"
A. Start the engine. Allow the engine to warm up to normal operating temperature .
B. Perform a "Cylinder Cutout Test". Check for a noticeable change in fuel usage.
Fuel Usage
Result: There is a noticeable change in fuel usage. The injectors are firing on all cylinders at this time.
Proceed to Test Step 3.
Result: There is not a noticeable change in fuel usage.
Repair: Verify that the valve lash for the suspect cylinder is OK. Then replace the suspect injector.
Verify that the repair eliminated the problem.
3. Check the Harness between the ECM and the Injector Connectors for an Open Circuit
A. Turn the main disconnect switch to the OFF position.
A strong electrical shock hazard is present if the keyswitch is not turned off.
B. Disconnect the harness connectors for the affected cylinder at the cylinder head.
C. Fabricate a jumper wire that is long enough to create a test circuit across the harness connector at the cylinder head. Crimp connector pins to each end of the jumper wire.
D. Connect the jumper wire between terminal locations 1 (supply) and 2 (return). This test will effectively create a short circuit for the cylinder.
E. Restore the electrical power to the ECM.
F. Perform the "Injector Solenoid Test" at least two times.
Harness
Result: Cat ET displays "Short" for the cylinder with the jumper wire. The harness is OK. Remove the jumper wire. Connect the harness connectors.
Proceed to Test Step 4.
Result: Cat ET displays "Open" for the cylinder with the jumper wire. The ECM did not detect the jumper wire. There is an open circuit in the wiring harness.
Repair: Correct the problem with the harness. Replace parts, if necessary. Start the engine.
Verify that the repair eliminated the problem.
4. Check the Harness between the ECM and the Injector Connectors for a Short Circuit
A. Turn the main disconnect switch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned off.
B. Disconnect the harness connectors for the injector solenoid at the cylinder head. There will then be an open circuit at the harness connector.
C. Restore the electrical power to the ECM.
D. Perform the "Injector Solenoid Test" at least two times.
Harness
Result: The suspect cylinder indicates "Open" on Cat ET. The harness is OK. Connect the harness connectors.
Proceed to Test Step 5.
Result: