C175-16 Petroleum Engine Caterpillar

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

Table 1

Diagnostic Codes Table
J1939 Code and Description	CDL Code and Description	System Response
651-2 Engine Injector Cylinder #01 : Erratic, Intermittent, or Incorrect	1-2 Cylinder #1 Injector : Erratic, Intermittent, or Incorrect	The Electronic Control Module (ECM) the injector solenoid that cannot be accurately interpreted. The ECM receives a signal from the injector solenoid that is invalid. The code is logged. The ECM continues to energize the injector solenoid.
652-2 Engine Injector Cylinder #02 : Erratic, Intermittent, or Inc	2-2 Cylinder #2 Injector : Erratic, Intermittent, or Incorrect
653-2 Engine Injector Cylinder #03 : Erratic, Intermittent, or Incorrect	3-2 Cylinder #3 Injector : Erratic, Intermittent, or Incorrect
654-2 Engine Injector Cylinder #04 : Erratic, Intermittent, or Incorrect	4-2 Cylinder #4 Injector : Erratic, Intermittent, or Incorrect
655-2 Engine Injector Cylinder #04 : Erratic, Intermittent, or Incorrect	5-2 Cylinder #5 Injector : Erratic, Intermittent, or Incorrect
656-2 Engine Injector Cylinder #06 : Erratic, Intermittent, or Incorrect	6-2 Cylinder #6 Injector : Erratic, Intermittent, or Incorrect
657-2 Engine Injector Cylinder #07 : Erratic, Intermittent, or Incorrect	7-2 Cylinder #7 Injector : Erratic, Intermittent, or Incorrect
658-2 Engine Injector Cylinder #08 : Erratic, Intermittent, or Incorrect	8-2 Cylinder #8 Injector : Erratic, Intermittent, or Incorrect
659-2 Engine Injector Cylinder #09 : Erratic, Intermittent, or Incorrect	9-2 Cylinder #9 Injector : Erratic, Intermittent, or Incorrect
660-2 Engine Injector Cylinder #10 : Erratic, Intermittent, or Incorrect	10-2 Cylinder #10 Injector : Erratic, Intermittent, or Incorrect
661-2 Engine Injector Cylinder #11 : Erratic, Intermittent, or Incorrect	11-2 Cylinder #11 Injector : Erratic, Intermittent, or Incorrect
662-2 Engine Injector Cylinder #12 : Erratic, Intermittent, or Incorrect	12-2 Cylinder #12 Injector : Erratic, Intermittent, or Incorrect
663-2 Engine Injector Cylinder #13 : Erratic, Intermittent, or Incorrect	13-2 Cylinder #13 Injector : Erratic, Intermittent, or Incorrect
664-2 Engine Injector Cylinder #14 : Erratic, Intermittent, or Incorrect	14-2 Cylinder #14 Injector : Erratic, Intermittent, or Incorrect
665-2 Engine Injector Cylinder #15 : Erratic, Intermittent, or Incorrect	15-2 Cylinder #15 Injector : Erratic, Intermittent, or Incorrect
666-2 Engine Injector Cylinder #16 : Erratic, Intermittent, or Incorrect	16-2 Cylinder #16 Injector : Erratic, Intermittent, or Incorrect
651-5 Engine Injector Cylinder #01 : Current Below Normal	1-5 Cylinder #1 Injector : Current Below Normal	The ECM detects a low current in the circuit for the injector solenoid. The code is logged. The ECM continues the attempt to energize the solenoid circuit until the circuit is repaired.
652-5 Engine Injector Cylinder #02 : Current Below Normal	2-5 Cylinder #2 Injector : Current Below Normal
653-2 Engine Injector Cylinder #03 : Erratic, Intermittent, or Incorrect	3-5 Cylinder #3 Injector : Current Below Normal
654-5 Engine Injector Cylinder #04 : Current Below Normal	4-5 Cylinder #4 Injector : Current Below Normal
655-5 Engine Injector Cylinder #05 : Current Below Normal	5-5 Cylinder #5 Injector : Current Below Normal
656-5 Engine Injector Cylinder #06 : Current Below Normal	6-5 Cylinder #6 Injector : Current Below Normal
657-5 Engine Injector Cylinder #07 : Current Below Normal	7-5 Cylinder #7 Injector : Current Below Normal
658-5 Engine Injector Cylinder #08 : Current Below Normal	8-5 Cylinder #8 Injector : Current Below Normal
659-5 Engine Injector Cylinder #09 : Current Below Normal	9-5 Cylinder #9 Injector : Current Below Normal
660-5 Engine Injector Cylinder #10 : Current Below Normal	10-5 10-5
661-5 Engine Injector Cylinder #11 : Current Below Normal	11-5 Cylinder #11 Injector : Current Below Normal
662-5 Engine Injector Cylinder #12 : Current Below Normal	12-5 Cylinder #12 Injector : Current Below Normal
663-5 Engine Injector Cylinder #13 : Current Below Normal	13-5 Cylinder #13 Injector : Current Below Normal
664-5 Engine Injector Cylinder #14 : Current Below Normal	14-5 Cylinder #14 Injector : Current Below Normal
665-5 Engine Injector Cylinder #15 : Current Below Normal	15-5 Cylinder #15 Injector : Current Below Normal
666-5 Engine Injector Cylinder #16 : Current Below Normal	16-5 Cylinder #16 Injector : Current Below Normal
651-6 Engine Injector Cylinder #01 : Current Above Normal	1-6 Cylinder #1 Injector : Current Above Normal	The ECM detects a high current in the circuit for the injector solenoid. The code is logged. The ECM disables this solenoid circuit. The ECM will periodically attempt to energize the solenoid circuit until the circuit is repaired.
652-6 Engine Injector Cylinder #02 : Current Above Normal	2-6 Cylinder #2 Injector : Current Above Normal
653-6 Engine Injector Cylinder #03 : Current Above Normal	3-6 Cylinder #3 Injector : Current Above Normal
654-6 Engine Injector Cylinder #04 : Current Above Normal	4-6 Cylinder #4 Injector : Current Above Normal
655-6 Engine Injector Cylinder #05 : Current Above Normal	5-6 Cylinder #5 Injector : Current Above Normal
656-6 Engine Injector Cylinder #06 : Current Above Normal	6-6 Cylinder #6 Injector : Current Above Normal
657-6 Engine Injector Cylinder #07 : Current Above Normal	7-6 Cylinder #7 Injector : Current Above Normal
658-6 Engine Injector Cylinder #08 : Current Above Normal	8-6 Cylinder #8 Injector : Current Above Normal
659-6 Engine Injector Cylinder #09 : Current Above Normal	9-6 Cylinder #9 Injector : Current Above Normal
660-6 Engine Injector Cylinder #10 : Current Above Normal	10-6 Cylinder #10 Injector : Current Above Normal
661-6 Engine Injector Cylinder #11 : Current Above Normal	11-6 Cylinder #11 Injector : Current Above Normal
662-6 Engine Injector Cylinder #12 : Current Above Normal	12-6 Cylinder #12 Injector : Current Above Normal
663-6 Engine Injector Cylinder #13 : Current Above Normal	13-6 Cylinder #13 Injector : Current Above Normal
664-6 Engine Injector Cylinder #14 : Current Above Normal	14-6 Cylinder #14 Injector : Current Above Normal
665-6 Engine Injector Cylinder #15 : Current Above Normal	15-6 Cylinder #15 Injector : Current Above Normal
666-6 Engine Injector Cylinder #16 : Current Above Normal	16-6 Cylinder #16 Injector : Current Above Normal
651-7 Engine Injector Cylinder #01 : Not Responding Properly	1-7 Cylinder #1 Injector : Not Responding Properly	The ECM has determined that the mechanical wear for the injector is out of specifications. The code is logged. The ECM continues to energize the injector solenoid.
652-7 Engine Injector Cylinder #02 : Not Responding Properly	2-7 Cylinder #2 Injector : Not Responding Properly
653-7 Engine Injector Cylinder #03 : Not Responding Properly	3-7 Cylinder #3 Injector : Not Responding Properly
654-7 Engine Injector Cylinder #04 : Not Responding Properly	4-7 Cylinder #4 Injector : Not Responding Properly
655-7 Engine Injector Cylinder #05 : Not Responding Properly	5-7 Cylinder #5 Injector : Not Responding Properly
656-7 Engine Injector Cylinder #06 : Not Responding Properly	6-7 Cylinder #6 Injector : Not Responding Properly
657-7 Engine Injector Cylinder #07 : Not Responding Properly	7-7 Cylinder #7 Injector : Not Responding Properly
658-7 Engine Injector Cylinder #08 : Not Responding Properly	8-7 Cylinder #8 Injector : Not Responding Properly
659-7 Engine Injector Cylinder #09 : Not Responding Properly	9-7 Cylinder #9 Injector : Not Responding Properly
660-7 Engine Injector Cylinder #10 : Not Responding Properly	10-7 Cylinder #10 Injector : Not Responding Properly
661-7 Engine Injector Cylinder #11 : Not Responding Properly	11-7 Cylinder #11 Injector : Not Responding Properly
662-7 Engine Injector Cylinder #12 : Not Responding Properly	12-7 Cylinder #12 Injector : Not Responding Properly
663-7 Engine Injector Cylinder #13 : Not Responding Properly	13-7 Cylinder #13 Injector : Not Responding Properly
664-7 Engine Injector Cylinder #14 : Not Responding Properly	14-7 Cylinder #14 Injector : Not Responding Properly
665-7 Engine Injector Cylinder #15 : Not Responding Properly	15-7 Cylinder #15 Injector : Not Responding Properly
666-7 Engine Injector Cylinder #16 : Not Responding Properly	16-7 Cylinder #16 Injector : Not Responding Properly

Cat ET includes the following tests that will aid in troubleshooting injector solenoids:

Note: Dual data link communications must be established between the service tool and the engine ECM prior to gaining access to some of the following tests. For information on dual data link communications, refer to Troubleshooting, "Electronic Service Tools" for details.

Cylinder Cutout Test - The "Cylinder Cutout Test" is used on an engine to determine the individual cylinder performance while the engine is running. As one or more cylinders are cut out during the test, the "Cylinder Cutout Test" uses "Fuel Position" to evaluate the performance of the cylinders. As different cylinders are cut out, a comparison of the change in fuel injection delivery is used to identify cylinders that are weak or misfiring. When a malfunctioning injector is cut out, the increase in fuel delivery is less than the increase for a cylinder that is performing normally. One reason for a cylinder that is weak or misfiring is an injector that is malfunctioning.

Injector Solenoid Test - This test identifies an open circuit or a short circuit in the circuits for the injector solenoids. The test is performed while the engine is not running. The "Injector Solenoid Test" briefly activates each solenoid. A good solenoid will create an audible click when the solenoid is activated. Cat ET indicates the status of the solenoid as "OK", "Open", or "Short".

Fuel System Verification Test - This test evaluates the health of each injector. The test determines if an injector needs to be replaced. When the test is performed, Cat ET indicates the status of each injector as "Success" or "Failed". Perform this test immediately after an injector has been replaced. Also, perform this test if a -2 code or -7 code is active.

Note: The "Fuel System Verification Test" test must be performed when the engine is running and the coolant temperature is above 65 °C (149 °F).

Note: Two injector solenoids may share a common supply wire. For this reason, an open circuit or a short circuit in a supply wire could cause diagnostic codes for two cylinders. Refer to Illustration 2 for the schematic that is for the injector solenoids.

Illustration 1	g02783418
Schematic of the injector solenoids circuits (control assembly input connectors) if equipped with A4 ECM

Illustration 2	g02783419
Schematic of the injector solenoids circuits (control assembly output connectors) if equipped with A4 ECM

Illustration 3	g06320858
Schematic of the injector solenoids circuits (control assembly output connectors) if equipped with A5 ECM

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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.

Table 2

Troubleshooting Test Steps	Values	Results
1. Check for Diagnostic Codes A. Establish communication between Cat ET and the engine ECM. Cat ET must be configured for Dual Data Link Communications to perform this procedure. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Determine the diagnostic code that relates to an injector.	Codes	Results: A -2 code or a -7 code is present. Repair: Perform the following procedure: 1. Do not clear the diagnostic code. 2. Access the Fuel System Verification Test by accessing the following display screens: - Diagnostics - Diagnostic Tests - Fuel System Verification Test 3. Perform the Fuel System Verification Test. If the injector passes the test, the injector is OK. Cat ET will clear the code. 4. If the injector fails the test, perform the following procedure: a. Replace the injector. b. Flash program the trim file for the new injector into the ECM. Refer to Troubleshooting, "Injector Trim File - Install", if necessary. c. Perform the Fuel System Verification Test again. This test will clear the active diagnostic code for the new injector. Verify that the original condition has been resolved. -5 or -6 Diagnostic Code Proceed to Test Step 2
2. Determine if the Diagnostic Code is Active or Logged A. Start the engine. Allow the engine to warm up to normal operating temperature 77 °C (171 °F) B. Determine if the -5 or -6 code is active or logged.	Code is active or logged	Results: Logged code - There is a logged diagnostic code. Do not turn off the engine. Proceed to Test Step 3. Results: Active code - There is an active diagnostic code. Do not turn off the engine. Proceed to Test Step 5
3. Check the External Engine Harness A. Inspect the injector wiring harness between the ECM and the valve cover for the affected injector. Look for these problems: - Improper routing of the wire harness - Missing clamps or other hardware - Loose connectors or damaged connectors - Damage that is caused by excessive heat - Damage that is caused by chafing B. Slowly wiggle the wiring harness and the connectors between the P2 connector and the control assembly input connector. Also, wiggle the wiring harness and the connectors between the control assembly output connector and the valve cover. Pay particular attention to the wiring near each connector. Look for activation of the diagnostic code as you wiggle the wiring. Continue with this procedure if the code does not become active. If the code becomes active, note the location of the problem. Proceed to the appropriate result for this Test Step. C. Refer to the appropriate schematic diagram. Identify the wires at each connector that relate to the cylinder that has the code. Perform the following procedure for the wires at each connector: a. Inspect the seal around each wire. Verify that the seal is sealing correctly. b. Pull on each wire to verify that the wire and the terminal are correctly installed.	Harness	Results: The external engine harness is OK. Note the number of the cylinder that has the logged diagnostic code. Stop the engine. Proceed to Test Step 4 Results: A problem with the external engine harness has been identified. Repair: Stop the engine. Repair the wiring problem. Replace parts, if necessary. Start the engine. Verify that the problem is resolved.
4. Check the Harness Under the Valve Cover for a Problem A. Remove the valve cover of the affected cylinder. B. Carefully perform a visual inspection of the wiring harness under the valve cover. Look for the following problems: - Improper routing of the wire harness - Missing clamps or other hardware - Loose connectors or damaged connectors - Damage that is caused by excessive heat - Damage that is caused by chafing C. Inspect the connectors on the harness under the valve cover. Perform the following procedure on each wire that relates to the cylinder that has the code: a. Inspect the seal around each wire. Verify that the seal is sealing correctly. b. Pull on each wire to verify that the wire and the terminal are correctly installed. c. Disconnect the harness connector from the suspect injector. Carefully inspect each terminal for debris, for moisture, and for corrosion. Verify that the seals and wedges are properly installed. d. Connect the harness connector to the injector. Verify that both clips work correctly.	Harness	Results: The wiring harness under the valve cover appears to be OK. Repair: Perform the following procedure: 1. Replace the injector that relates to the logged code. Install the valve cover. 2. Load the trim file for the new injector into the ECM. 3. Use Cat ET to perform a Fuel System Verification Test. This test will clear the active diagnostic code for the new injector. Results: There is a problem with the wiring harness under the valve cover. Repair: Correct the problem. Replace parts, if necessary. Install the valve cover. Start the engine. Allow the engine to warm up to normal operating temperature. Verify that the code does not recur.
5. Check the Integrity of the External Engine Harness A. Wiggle the injector wiring harness between the ECM and the valve cover. Look for these problems. - Improper routing of the wire harness - Missing clamps or other hardware - Loose connectors or damaged connectors - Damage that is caused by excessive heat - Damage that is caused by chafing B. Refer to the appropriate schematic diagram. Identify the wires at each connector that relate to the cylinder that has the code. Perform the following procedure for the wires at each connector: a. Inspect the seal around each wire. Verify that the seal is sealing correctly. b. Pull on each wire to verify that the wire and the terminal are correctly installed.	External engine harness	Results: The code becomes inactive when the wiring is checked. Repair: Stop the engine. Repair the problem with the harness. Replace parts, if necessary. Start the engine. Verify that the problem is resolved. Results: A -5 code remains active. Note the cylinder that has the active -5 code. Stop the engine. Proceed to Test Step 6 Results: A -6 code remains active. Note the cylinder that has the active -6 code. Stop the engine. Proceed to Test Step 8
6. Check the External Engine Harness for an Open Circuit A. Turn the keyswitch 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. Turn the keyswitch to the ON position. F. Perform the "Injector Solenoid Test" at least two times.	Open circuit	Results: Cat ET displays "Short" for the cylinder with the jumper wire. The harness between the ECM connector and the harness connector at the cylinder head is OK. Remove the jumper wire. Connect the harness connectors. Proceed to Test Step 7 Results: 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 between the J2 ECM connector and the harness connector at the cylinder head. Repair The problem with the harness. Replace parts, if necessary. Start the engine. Verify that the problem is resolved.
7. Check the Injector Harness under the Valve Cover for an Open Circuit A. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned off. B. Remove the valve cover. C. Carefully perform a visual inspection of the wiring harness under the valve cover. Look for the following problems: - Improper routing of the wire harness - Missing clamps or other hardware - Loose connectors or damaged connectors - Damage that is caused by excessive heat - Damage that is caused by chafing D. Inspect the connectors on the harness under the valve cover. Perform the following procedure on each wire that relates to the cylinder that has the code: a. Inspect the seal around each wire. Verify that the seal is sealing correctly. b. Pull on each wire to verify that the wire and the terminal are correctly installed. c. Disconnect the harness connector from the suspect injector. Carefully inspect each terminal for debris, for moisture, and for corrosion. Verify that the seals and wedges are properly installed. E. Connect a jumper wire across the terminals in the harness connector for the cylinder that has the code. The jumper wire will effectively replace the injector solenoid with a short circuit. F. Turn the keyswitch to the ON position. G. Perform the "Injector Solenoid Test" at least two times.	Open circuit	Results: Cat ET displays "Short" for the cylinder with the jumper wire. The wiring is OK. There is a problem with the injector. Repair: Perform the following procedure: 1. Replace the faulty injector. Install the valve cover. 2. Load the trim file for the new injector into the ECM. 3. Use Cat ET to perform a Fuel System Verification Test. This test will clear the active diagnostic code for the new injector. Results: Cat ET displays "Open" for the cylinder with the jumper wire. There is a problem with the injector harness under the valve cover. There may be a problem with a connector. Repair The wiring and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.
8. Check the External Engine Harness for a Short Circuit A. Turn the keyswitch 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. The jumper wire will effectively create an open circuit at the harness connector. C. Turn the keyswitch to the ON position. D. Perform the "Injector Solenoid Test" at least two times.	Short circuit	Results: The suspect cylinder indicates "Open" on Cat ET. The engine harness is OK. Connect the harness connectors. Proceed to Test Step 9 Results: A cylinder indicates "Short" on Cat ET. There is a problem with the engine harness between the J2 connector and the valve cover harness. Repair The problem with the harness. Replace parts, if necessary. Start the engine. Verify that the problem is resolved
9. Check the Harness under the Valve Cover for a Short Circuit A. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned off. B. Remove the valve cover. C. Disconnect the harness connector for each injector solenoid that indicates a "Short" on Cat ET. Ensure that each disconnected connector does not touch other components and create a short circuit. D. Turn the keyswitch to the ON position. E. Perform the "Injector Solenoid Test" at least two times.	Short circuit	Results: All the injector solenoids that were disconnected indicate "Open" on Cat ET. Repair: Perform the following procedure: 1. Replace the injector that relates to the logged code. Install the valve cover. 2. Use Cat ET to perform a Fuel System Verification Test. This test will clear the active diagnostic code for the new injector. Results: At least one of the injector solenoids that were disconnected still indicate "Short" on Cat ET. There is a problem with the wiring harness inside the valve cover. There may be a problem with a connector. Repair: Inspect the connectors for moisture and for corrosion. Repair the wiring and/or the connector, when possible. Replace parts, if necessary. 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).