C175-16 Locomotive 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 is active or easily repeated.

Table 1

Diagnostic Codes Table
Code and Description	Conditions which Generate this Code	System Response
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.
2-5 Cylinder #2 Injector : Current Below Normal
3-5 Cylinder #3 Injector : Current Below Normal
4-5 Cylinder #4 Injector : Current Below Normal
5-5 Cylinder #5 Injector : Current Below Normal
6-5 Cylinder #6 Injector : Current Below Normal
7-5 Cylinder #7 Injector : Current Below Normal
8-5 Cylinder #8 Injector : Current Below Normal
9-5 Cylinder #9 Injector : Current Below Normal
10-5 Cylinder #10 Injector : Current Below Normal
11-5 Cylinder #11 Injector : Current Below Normal
12-5 Cylinder #12 Injector : Current Below Normal
13-5 Cylinder #13 Injector : Current Below Normal
14-5 Cylinder #14 Injector : Current Below Normal
15-5 Cylinder #15 Injector : Current Below Normal
16-5 Cylinder #16 Injector : Current Below 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.
2-6 Cylinder #2 Injector : Current Above Normal
3-6 Cylinder #3 Injector : Current Above Normal
4-6 Cylinder #4 Injector : Current Above Normal
5-6 Cylinder #5 Injector : Current Above Normal
6-6 Cylinder #6 Injector : Current Above Normal
7-6 Cylinder #7 Injector : Current Above Normal
8-6 Cylinder #8 Injector : Current Above Normal
9-6 Cylinder #9 Injector : Current Above Normal
10-6 Cylinder #10 Injector : Current Above Normal
11-6Cylinder #11 Injector : Current Above Normal
12-6 Cylinder #12 Injector : Current Above Normal
13-6 Cylinder #13 Injector : Current Above Normal
14-6 Cylinder #14 Injector : Current Above Normal
15-6 Cylinder #15 Injector : Current Above Normal
16-6 Cylinder #16 Injector : Current Above Normal

Background Information

Perform this procedure during operating conditions that are identical to the operating conditions that exist when the problem occurs. Typically, problems with the injector solenoid occur when the engine is warmed up and/or when the engine is under vibration (heavy loads). The wiring and/or the connectors may have problems that only occur during vibration.

These engines have fuel injectors that are electronically controlled. A solenoid is used to actuate the injector. The solenoid is mounted on top of the fuel injector body. The ECM sends a 105 V pulse to the injector solenoid. The pulse is sent at the proper time and for the correct duration for any given engine load and speed.

Trim Files

When an injector is replaced, program the new injector code into the ECM. Refer to Troubleshooting, "Injector Trim File - Install" for information that is related to trim files. If the ECM is replaced, all of the injector codes must be programmed into the new ECM. Refer to Troubleshooting, "ECM - Configure" for information that is related to the configuration of a new ECM.

Diagnostic Tests that are Available on Caterpillar Electronic Technician (ET)

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 in order 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 3 for the schematic that is for the injector solenoids.

Illustration 1	g01270037
Schematic of the injector solenoids circuits (control assembly input connectors)

Illustration 2	g03377815
Location of the ECM connectors (Control box may not be located on engine.) (1) Right rail connector (2) J2/P2 ECM connector (3) Left rail connector

Illustration 3	g01270451
Terminal locations at the P2 ECM connector that are associated with the injector solenoids (P2-18) Injector cylinder 11 return (P2-22) Injector cylinder 7 return (P2-31) Injector cylinder 9 return (P2-50) Injector cylinder 5 return (P2-61) Injector cylinder 14, 16 supply (P2-67) Injector cylinder 9 ,11 supply (P2-68) Injector cylinder 5, 7 supply (P2-75) Injector cylinder 10 return (P2-77) Injector cylinder 2, 4 supply (P2-87) Injector cylinder 12 return (P2-88) Injector cylinder 6 return (P2-98) Injector cylinder 8 return (P2-101) Injector cylinder 14 return (P2-103) Injector cylinder 16 return (P2-104) Injector cylinder 1, 3 supply (P2-106) Injector cylinder 13 return (P2-108) Injector cylinder 15 return (P2-109) Injector cylinder 6, 8 supply (P2-111) Injector cylinder 2 return (P2-113) Injector cylinder 4 return (P2-115) Injector cylinder 13, 15 supply (P2-116) Injector cylinder 1 return (P2-118) Injector cylinder 3 return (P2-120) Injector cylinder 10, 12 supply

Illustration 4	g01527050
Left rail connector (Terminal 1) Injector cylinder 2, 4 supply (Terminal 2) Injector cylinder 2 return (Terminal 3) Injector cylinder 4 return (Terminal 4) Injector cylinder 6, 8 supply (Terminal 5) Injector cylinder 6 return (Terminal 6) Injector cylinder 8 return (Terminal 7) Injector cylinder 10, 12 supply (Terminal 8) Injector cylinder 10 return (Terminal 9) Injector cylinder 12 return (Terminal 10) Injector cylinder 14, 16 supply (Terminal 11) Injector cylinder 14 return (Terminal 12) Injector cylinder 16 return

Illustration 5	g01527045
Right rail connector (Terminal 1) Injector cylinder 1, 3 supply (Terminal 2) Injector cylinder 1 return (Terminal 3) Injector cylinder 3 return (Terminal 4) Injector cylinder 5, 7supply (Terminal 5) Injector cylinder 5 return (Terminal 6) Injector cylinder 7 return (Terminal 7) Injector cylinder 9, 11 supply (Terminal 8) Injector cylinder 9 return (Terminal 9) Injector cylinder 11 return (Terminal 10) Injector cylinder 13, 15 supply (Terminal 11) Injector cylinder 13 return (Terminal 12) Injector cylinder 15 return

Illustration 6	g01527037
Location of the fuel injector connector at the cylinder head

Illustration 7	g01271125
Terminal locations for the injector harness at the cylinder head (Terminal 1) Supply (Terminal 2) Return

Illustration 8	g01271655
Terminal locations at the injector connector (Terminal 1) Supply (Terminal 2) Return

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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. 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 2. Results: Active code - There is an active diagnostic code. Do not turn off the engine. Proceed to Test Step 4
2. 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 in order 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 3 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.
3. 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 in order 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: Not OK -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.
4. 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 in order to verify that the wire and the terminal are correctly installed.	External engine harness	Results: OK - 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: Not OK - Active -5 Code A -5 code remains active. Note the cylinder that has the active -5 code. Stop the engine. Proceed to Test Step 5 Results: Not OK - Active -6 Code - A -6 code remains active. Note the cylinder that has the active -6 code. Stop the engine. Proceed to Test Step 7

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

Table 3

Troubleshooting Test Steps	Values	Results
5. 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 6 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.

Show/hide table

Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

Table 4

Troubleshooting Test Steps	Values	Results
6. 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 in order 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: Not OK -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.

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

Table 5

Troubleshooting Test Steps	Values	Results
7. 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 8 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

Show/hide table

Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

Table 6

Troubleshooting Test Steps	Values	Results
8. 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: OK All of 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: Not OK - 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.