C175 Oil&Gas Offshore Engine Caterpillar

Injector Solenoid - Test

Usage:

Use this procedure to troubleshoot the engine electrical system if a problem is suspected with the injectors, or if any of the diagnostic codes in Table 1 are active or easily repeated.

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Table 1
J1939 Code and Description	CDL Code and Description	Comments
651-2 Engine Injector Cylinder #01 : Erratic, Intermittent, or Incorrect	1-2 Cylinder #1 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
651-5 Engine Injector Cylinder #01 : Current Below Normal	1-5 Cylinder #1 Injector : Current Below Normal	The ECM detects an open circuit.
651-6 Engine Injector Cylinder #01 : Current Above Normal	1-6 Cylinder #1 Injector : Current Above Normal	The ECM detects a short circuit.
651-7 Engine Injector Cylinder #01 : Not Responding Properly	1-7 Cylinder #1 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
651-20 Engine Injector Cylinder #01 : Data Drifted High	1-20 Cylinder #1 Injector : Data Drifted High	The ECM has detected under fueling injector.
651-21 Engine Injector Cylinder #01 : Data Drifted Low	1-21 Cylinder #1 Injector : Data Drifted Low	The ECM has detected over fueling injector.
652-2 Engine Injector Cylinder #02 : Erratic, Intermittent, or Incorrect	2-2 Cylinder #2 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
652-5 Engine Injector Cylinder #02 : Current Below Normal	2-5 Cylinder #2 Injector : Current Below Normal	The ECM detects an open circuit.
652-6 Engine Injector Cylinder #02 : Current Above Normal	2-6 Cylinder #2 Injector : Current Above Normal	The ECM detects a short circuit.
652-7 Engine Injector Cylinder #02 : Not Responding Properly	2-7 Cylinder #2 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
652-20 Engine Injector Cylinder #02 : Data Drifted High	2-20 Cylinder #2 Injector : Data Drifted High	The ECM has detected under fueling injector.
652-21 Engine Injector Cylinder #02 : Data Drifted Low	2-21 Cylinder #2 Injector : Data Drifted Low	The ECM has detected over fueling injector.
653-2 Engine Injector Cylinder #03 : Erratic, Intermittent, or Incorrect	3-2 Cylinder #3 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
653-5 Engine Injector Cylinder #03 : Current Below Normal	3-5 Cylinder #3 Injector : Current Below Normal	The ECM detects an open circuit.
653-6 Engine Injector Cylinder #03 : Current Above Normal	3-6 Cylinder #3 Injector : Current Above Normal	The ECM detects a short circuit.
653-7 Engine Injector Cylinder #03 : Not Responding Properly	3-7 Cylinder #3 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
653-20 Engine Injector Cylinder #03 : Data Drifted High	3-20 Cylinder #3 Injector : Data Drifted High	The ECM has detected under fueling injector.
653-21 Engine Injector Cylinder #03 : Data Drifted Low	3-21 Cylinder #3 Injector : Data Drifted Low	The ECM has detected over fueling injector.
654-2 Engine Injector Cylinder #04 : Erratic, Intermittent, or Incorrect	4-2 Cylinder #4 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
654-5 Engine Injector Cylinder #04 : Current Below Normal	4-5 Cylinder #4 Injector : Current Below Normal	The ECM detects open circuit.
654-6 Engine Injector Cylinder #04 : Current Above Normal	4-6 Cylinder #4 Injector : Current Above Normal	The ECM detects a short circuit.
654-7 Engine Injector Cylinder #04 : Not Responding Properly	4-7 Cylinder #4 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
654-20 Engine Injector Cylinder #04 : Data Drifted High	4-20 Cylinder #4 Injector : Data Drifted High	The ECM has detected under fueling injector.
654-21 Engine Injector Cylinder #04 : Data Drifted Low	4-21 Cylinder #4 Injector : Data Drifted Low	The ECM has detected over fueling injector.
655-2 Engine Injector Cylinder #05 : Erratic, Intermittent, or Incorrect	5-2 Cylinder #5 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
655-5 Engine Injector Cylinder #05 : Current Below Normal	5-5 Cylinder #5 Injector : Current Below Normal	The ECM detects an open circuit.
655-6 Engine Injector Cylinder #05 : Current Above Normal	5-6 Cylinder #5 Injector : Current Above Normal	The ECM detects a short circuit.
655-7 Engine Injector Cylinder #05 : Not Responding Properly	5-7 Cylinder #5 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
655-20 Engine Injector Cylinder #05 : Data Drifted High	5-20 Cylinder #5 Injector : Data Drifted High	The ECM has detected under fueling injector.
655-21 Engine Injector Cylinder #05 : Data Drifted Low	5-21 Cylinder #5 Injector : Data Drifted Low	The ECM has detected over fueling injector.
656-2 Engine Injector Cylinder #06 : Erratic, Intermittent, or Incorrect	6-2 Cylinder #6 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
656-5 Engine Injector Cylinder #06 : Current Below Normal	6-5 Cylinder #6 Injector : Current Below Normal	The ECM detects an open circuit.
656-6 Engine Injector Cylinder #06 : Current Above Normal	6-6 Cylinder #6 Injector : Current Above Normal	The ECM detects a short circuit.
656-7 Engine Injector Cylinder #06 : Not Responding Properly	6-7 Cylinder #6 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
656-20 Engine Injector Cylinder #06 : Data Drifted High	6-20 Cylinder #6 Injector : Data Drifted High	The ECM has detected under fueling injector.
656-21 Engine Injector Cylinder #06 : Data Drifted Low	6-21 Cylinder #6 Injector : Data Drifted Low	The ECM has detected over fueling injector.
657-2 Engine Injector Cylinder #07 : Erratic, Intermittent, or Incorrect	7-2 Cylinder #7 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
657-5 Engine Injector Cylinder #07 : Current Below Normal	7-5 Cylinder #7 Injector : Current Below Normal	The ECM detects an open circuit.
657-6 Engine Injector Cylinder #07 : Current Above Normal	7-6 Cylinder #7 Injector : Current Above Normal	The ECM detects a short circuit.
657-7 Engine Injector Cylinder #07 : Not Responding Properly	7-7 Cylinder #7 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
657-20 Engine Injector Cylinder #07 : Data Drifted High	7-20 Cylinder #7 Injector : Data Drifted High	The ECM has detected under fueling injector.
657-21 Engine Injector Cylinder #07 : Data Drifted Low	7-21 Cylinder #7 Injector : Data Drifted Low	The ECM has detected over fueling injector.
658-2 Engine Injector Cylinder #08 : Erratic, Intermittent, or Incorrect	8-2 Cylinder #8 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
658-5 Engine Injector Cylinder #08 : Current Below Normal	8-5 Cylinder #8 Injector : Current Below Normal	The ECM detects an open circuit.
658-6 Engine Injector Cylinder #08 : Current Above Normal	8-6 Cylinder #8 Injector : Current Above Normal	The ECM detects a short circuit.
658-7 Engine Injector Cylinder #08 : Not Responding Properly	8-7 Cylinder #8 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
658-20 Engine Injector Cylinder #08 : Data Drifted High	8-20 Cylinder #8 Injector : Data Drifted High	The ECM has detected under fueling injector.
658-21 Engine Injector Cylinder #08 : Data Drifted Low	8-21 Cylinder #8 Injector : Data Drifted Low	The ECM has detected over fueling injector.
659-2 Engine Injector Cylinder #09 : Erratic, Intermittent, or Incorrect	9-2 Cylinder #9 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
659-5 Engine Injector Cylinder #09 : Current Below Normal	9-5 Cylinder #9 Injector : Current Below Normal	The ECM detects an open circuit.
659-6 Engine Injector Cylinder #09 : Current Above Normal	9-6 Cylinder #9 Injector : Current Above Normal	The ECM detects a short circuit.
659-7 Engine Injector Cylinder #09 : Not Responding Properly	9-7 Cylinder #9 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
659-20 Engine Injector Cylinder #09 : Data Drifted High	9-20 Cylinder #9 Injector : Data Drifted High	The ECM has detected under fueling injector.
659-21 Engine Injector Cylinder #09 : Data Drifted Low	9-21 Cylinder #9 Injector : Data Drifted Low	The ECM has detected over fueling injector.
660-2 Engine Injector Cylinder #10 : Erratic, Intermittent, or Incorrect	10-2 Cylinder #10 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
660-5 Engine Injector Cylinder #10 : Current Below Normal	10-5 Cylinder #10 Injector : Current Below Normal	The ECM detects an open circuit.
660-6 Engine Injector Cylinder #10 : Current Above Normal	10-6 Cylinder #10 Injector : Current Above Normal	The ECM detects a short circuit.
660-7 Engine Injector Cylinder #10 : Not Responding Properly	10-7 Cylinder #10 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
660-20 Engine Injector Cylinder #10 : Data Drifted High	10-20 Cylinder #10 Injector : Data Drifted High	The ECM has detected under fueling injector.
660-21 Engine Injector Cylinder #10 : Data Drifted Low	10-21 Cylinder #10 Injector : Data Drifted Low	The ECM has detected over fueling injector.
661-2 Engine Injector Cylinder #11 : Erratic, Intermittent, or Incorrect	11-2 Cylinder #11 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
661-5 Engine Injector Cylinder #11 : Current Below Normal	11-5 Cylinder #11 Injector : Current Below Normal	The ECM detects an open circuit.
661-6 Engine Injector Cylinder #11 : Current Above Normal	11-6 Cylinder #11 Injector : Current Above Normal	The ECM detects a short circuit.
661-7 Engine Injector Cylinder #11 : Not Responding Properly	11-7 Cylinder #11 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
661-20 Engine Injector Cylinder #11 : Data Drifted High	11-20 Cylinder #11 Injector : Data Drifted High	The ECM has detected under fueling injector.
661-21 Engine Injector Cylinder #11 : Data Drifted Low	11-21 Cylinder #11 Injector : Data Drifted Low	The ECM has detected over fueling injector.
662-2 Engine Injector Cylinder #12 : Erratic, Intermittent, or Incorrect	12-2 Cylinder #12 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
662-5 Engine Injector Cylinder #12 : Current Below Normal	12-5 Cylinder #12 Injector : Current Below Normal	The ECM detects an open circuit.
662-6 Engine Injector Cylinder #12 : Current Above Normal	12-6 Cylinder #12 Injector : Current Above Normal	The ECM detects a short circuit.
662-7 Engine Injector Cylinder #12 : Not Responding Properly	12-7 Cylinder #12 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
662-20 Engine Injector Cylinder #12 : Data Drifted High	12-20 Cylinder #12 Injector : Data Drifted High	The ECM has detected under fueling injector.
662-21 Engine Injector Cylinder #12 : Data Drifted Low	12-21 Cylinder #12 Injector : Data Drifted Low	The ECM has detected over fueling injector.
663-2 Engine Injector Cylinder #13 : Erratic, Intermittent, or Incorrect	13-2 Cylinder #13 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
663-5 Engine Injector Cylinder #13 : Current Below Normal	13-5 Cylinder #13 Injector : Current Below Normal	The ECM detects an open circuit.
663-6 Engine Injector Cylinder #13 : Current Above Normal	13-6 Cylinder #13 Injector : Current Above Normal	The ECM detects a short circuit.
663-7 Engine Injector Cylinder #13 : Not Responding Properly	13-7 Cylinder #13 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
663-20 Engine Injector Cylinder #13 : Data Drifted High	13-20 Cylinder #13 Injector : Data Drifted High	The ECM has detected under fueling injector.
663-21 Engine Injector Cylinder #13 : Data Drifted Low	13-21 Cylinder #13 Injector : Data Drifted Low	The ECM has detected over fueling injector.
664-2 Engine Injector Cylinder #14 : Erratic, Intermittent, or Incorrect	14-2 Cylinder #14 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
664-5 Engine Injector Cylinder #14 : Current Below Normal	14-5 Cylinder #14 Injector : Current Below Normal	The ECM detects an open circuit.
664-6 Engine Injector Cylinder #14 : Current Above Normal	14-6 Cylinder #14 Injector : Current Above Normal	The ECM detects a short circuit.
664-7 Engine Injector Cylinder #14 : Not Responding Properly	14-7 Cylinder #14 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
664-20 Engine Injector Cylinder #14 : Data Drifted High	14-20 Cylinder #14 Injector : Data Drifted High	The ECM has detected under fueling injector.
664-21 Engine Injector Cylinder #14 : Data Drifted Low	14-21 Cylinder #14 Injector : Data Drifted Low	The ECM has detected over fueling injector.
665-2 Engine Injector Cylinder #15 : Erratic, Intermittent, or Incorrect	15-2 Cylinder #15 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
665-5 Engine Injector Cylinder #15 : Current Below Normal	15-5 Cylinder #15 Injector : Current Below Normal	The ECM detects an open circuit.
665-6 Engine Injector Cylinder #15 : Current Above Normal	15-6 Cylinder #15 Injector : Current Above Normal	The ECM detects a short circuit.
665-7 Engine Injector Cylinder #15 : Not Responding Properly	15-7 Cylinder #15 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
665-20 Engine Injector Cylinder #15 : Data Drifted High	15-20 Cylinder #15 Injector : Data Drifted High	The ECM has detected under fueling injector.
665-21 Engine Injector Cylinder #15 : Data Drifted Low	15-21 Cylinder #15 Injector : Data Drifted Low	The ECM has detected over fueling injector.
666-2 Engine Injector Cylinder #16 : Erratic, Intermittent, or Incorrect	16-2 Cylinder #16 Injector : Erratic, Intermittent, or Incorrect	The ECM has detected that an injector or injectors are not responding as desired.
666-5 Engine Injector Cylinder #16 : Current Below Normal	16-5 Cylinder #16 Injector : Current Below Normal	The ECM detects an open circuit.
666-6 Engine Injector Cylinder #16 : Current Above Normal	16-6 Cylinder #16 Injector : Current Above Normal	The ECM detects a short circuit.
666-7 Engine Injector Cylinder #16 : Not Responding Properly	16-7 Cylinder #16 Injector : Not Responding Properly	The ECM has detected there is a problem with an injector.
666-20 Engine Injector Cylinder #16 : Data Drifted High	16-20 Cylinder #16 Injector : Data Drifted High	The ECM has detected under fueling injector.
666-21 Engine Injector Cylinder #16 : Data Drifted Low	16-21 Cylinder #16 Injector : Data Drifted Low	The ECM has detected over fueling injector.

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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.

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Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.

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NOTICE

Ensure that all adjustments and repairs that are carried out to the fuel system are performed by authorized personnel that have the correct training. Before beginning ANY work on the fuel system, refer to Operation and Maintenance Manual, "General Hazard Information and High-Pressure Fuel Lines" for safety information. Refer to Systems Operation, "Cleanliness of Fuel System Components" for detailed information on the standards of cleanliness that must be observed during ALL work on the fuel system.

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Illustration 1	g06320858
Schematic of the injector solenoids circuits

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Establish communication between Cat ET and the ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Determine if a code is active or logged.	Codes	Result: There are codes other than an injector code active or logged. Proceed to Test Step 2. Result: A -5 code or a -6 code is logged or active. Proceed to Test Step 2.
2. Inspect the Wiring Harness Between the ECM and the Valve Cover Base A. Turn the keyswitch to OFF. B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector. Perform a pull test on each of the wires that are associated with injector solenoids. D. Check the allen head screw on the ECM connector for the proper torque. E. Check the harness and wiring for abrasions and for pinch points from the valve cover base to the ECM.	Damaged wiring or connectors	Result: The connectors and the wiring appear to be OK. Proceed to Test Step 3. Result: There is a problem with the connectors and/or wiring. Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled. Perform an injector solenoid test to verify that the problem has been resolved.
3. Check the Harness between the ECM and the Valve Cover Base for an Open Circuit A. Turn the keyswitch to OFF. B. Remove electrical power from the engine ECM. C. Disconnect the connectors of the injector harness at the valve cover base. D. Fabricate a jumper wire long enough to create a short circuit on the different terminal locations at the connector of the injector harness. Crimp connector pins on both ends of the jumper wire. E. Insert one end of the jumper wire into the connector socket for the suspect injectors supply wire. Insert the other end of the jumper wire into the connector socket for the suspect injectors return wire. The jumper wire will bypass the injector solenoid. F. Restore electrical power to the engine ECM. G. Turn the keyswitch to ON. H. Perform the "Injector Solenoid Test" in Cat ET. I. Repeat this test for each suspect circuit. Stop the "Injector Solenoid Test" before handling the jumper wire. Restore the wiring to the original configuration.	Short circuit is detected	Result: Cat ET displays a -6 code for each circuit that was jumpered. Proceed to Test Step 4. Result: Cat ET does not display a -6 code for the cylinder with the jumper wire. Repair: Repair the harness or replace the harness between the ECM and the valve cover base. Perform an injector solenoid test to verify that the problem is resolved.
4. Check the Harness between the ECM and the Valve Cover Base for a Short Circuit A. Turn the keyswitch toOFF. B. Remove electrical power from the engine ECM. C. Disconnect the connectors of the injector harness at the valve cover base. D. Restore electrical power to the engine ECM. E. Turn the keyswitch to ON. F. Perform the Injector Solenoid Test at least two times.	Open circuit detected	Result: All cylinders indicate a -5 code on Cat ET. Proceed to Test Step 5. Result: One or more cylinders indicate a -6 code on Cat ET. Note the cylinders that indicate "Short". Repair: Repair the wiring or replace the wiring to the ECM. Perform an injector solenoid test to verify that the problem is resolved.
5. Inspect the Wiring Harness Between the Valve Cover Base and the Injectors A. Turn the keyswitch to OFF. B. Remove electrical power from the engine ECM. C. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. D. Perform a 45 N (10 lb) pull test on each of the wires that are associated with injector solenoids. E. Check the harness and wiring for abrasions and for pinch points from the valve cover base to the injectors.	Damaged wiring or connectors	Result: The connectors and the wiring appear to be OK. Proceed to Test Step 6. Result: There is a problem with the connectors and/or wiring. Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled. Perform an injector solenoid test to verify that the problem is resolved.
6. Check the Injector Harness under the Valve Cover for a Short Circuit A. Turn the keyswitch to OFF. B. Remove electrical power from the engine ECM. C. Remove the valve cover to gain access to the suspect injector. D. Disconnect the harness connector from the suspect injector. E. Inspect the seal around each wire. Verify that the seal is sealing correctly. F. Pull on each wire to verify that the wire and the terminal are correctly installed. G. Restore power to the ECM. H. Turn the keyswitch to ON. I. Activate the "Injector Solenoid Test". Allow the Injector Solenoid Test to continue until each solenoid is activated at least two times.	Open circuit detected	Result: Cat ET displays "Open" for the solenoid that is not connected. Proceed to Test Step 7. Result: Cat ET displays "Short" for the solenoid that is not connected. Repair: Repair the wiring and/or the connector, when possible. Replace the damaged parts as needed. Perform an injector solenoid test to verify that the problem is resolved.
7. Check the Injector Harness under the Valve Cover for an Open Circuit A. Turn the keyswitch to OFF. B. Remove electrical power from the engine ECM. C. Determine the appropriate terminals for the solenoid with the code. Connect a jumper wire between the terminal for the supply and the terminal for the return. The jumper wire will replace the injector solenoid with a short circuit. D. Turn the keyswitch to ON. E. Activate the "Injector Solenoid Test". Allow the Injector Solenoid Test to continue until each solenoid is activated at least two times.	Short circuit detected	Result: Cat ET displays "Short" for the connector that has the jumper wire. Proceed to Test Step 8. Result: Cat ET displays "Open" for the connector that has the jumper wire. Repair: Repair the harness or replace the harness under the valve cover. Perform an injector solenoid test to verify that the problem is resolved.
8. Check for a Short to Ground on the Return Circuit Under the Valve Cover. A. Turn the keyswitch to OFF. B. Disconnect the suspect injector to the wiring harness connector. C. Remove the valve cover and disconnect the injector that shares a power supply with the suspect injector. D. Disconnect the J2 connector from the engine ECM. E. Measure the resistance between the suspect injector RETURN wire at the wiring harness connector and a known good ground. F. Measure the resistance between the injector that shares the power supply RETURN wire at the wiring harness connector and a known good ground. Note: Refer to the appropriate wiring schematic to see which injectors share a power supply. On the C175-20 engine, Cylinders 9, 10, 19, and 20 do not have paired power supply circuits. These four cylinders have individual circuits for power and return.	Resistance	Result: The resistance between the RETURN wires on the injector harness and a known good ground is less than 10 K ohms. Proceed to Test Step 9. Result: The resistance between the RETURN wires on the injector harness and a known good ground is greater than 10 K ohms. Repair: Replace the suspect injector that was logging the code. Perform an "Injector Solenoid Test" using Cat ET to verify that the problem is resolved.
9. Check for a Short to Ground on the Return Circuit in the Wiring Harness A. Turn the keyswitch to OFF. B. Disconnect the injector connector at the valve cover connection for the suspect injector. C. Disconnect the injector connector at the valve cover connection for the injector that shares the power supply with the suspect injector. D. Disconnect the J2 connector from the engine ECM. E. Measure the resistance between the suspect injector RETURN wire at the valve cover wiring harness connector and a known good ground. F. Measure the resistance between the injector that shares the power supply RETURN wire at the valve cover wiring harness connector and a known good ground. Note: Refer to the appropriate wiring schematic to see which injectors share a power supply. On the C175-20 engine, Cylinders 9, 10, 19, and 20 do not have paired power supply circuits. These four cylinders have individual circuits for power and return.	Resistance	Result: The resistance between the RETURN wires on the injector valve cover harness and a known good ground is less than 10 K ohms. Repair: Repair or replace the engine wiring harness. Perform an "Injector Solenoid Test" using Cat ET to verify that the problem is resolved. Result: The resistance between the RETURN wire on the injector valve cover harness and a known good ground is greater than 10 K ohms. Repair: Repair or replace the wiring harness under the valve cover. Perform an "Injector Solenoid Test" using Cat ET to verify that the problem is resolved.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).