C7 and C9 Industrial Engines Troubleshooting – Injector Solenoid – Test

Use this procedure for the following conditions:

A suspected problem with an injector solenoid
You have been directed to this procedure from Troubleshooting, “Troubleshooting without a Diagnostic Code”.
There is an active diagnostic code for an injector solenoid.

Use this procedure for the following diagnostic codes:

1-05 Cylinder #1 Injector open circuit
1-06 Cylinder #1 Injector short
2-05 Cylinder #2 Injector open circuit
2-06 Cylinder #2 Injector short
3-05 Cylinder #3 Injector open circuit
3-06 Cylinder #3 Injector short
4-05 Cylinder #4 Injector open circuit
4-06 Cylinder #4 Injector short
5-05 Cylinder #5 Injector open circuit
5-06 Cylinder #5 Injector short
6-05 Cylinder #6 Injector open circuit
6-06 Cylinder #6 Injector short

Perform this procedure under conditions that are identical to the 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).

These engines have Electronic Unit Injectors (EUI) that are hydraulically actuated and electronically controlled. The Engine Control Module (ECM) sends a high voltage signal to each injector solenoid. The signal is sent with the proper injection duration and injection timing for the current engine load and speed. The injector solenoid is mounted on top of the fuel injector body.

If an open circuit condition is detected in the solenoid circuit, a diagnostic code is generated. The ECM will continue to try to fire the injector. If a short circuit condition is detected, a diagnostic code is generated. The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit condition remains, this sequence of events will be repeated until the problem is corrected.

Two injector solenoids share a supply wire. For this reason, an open circuit or a short circuit in a supply wire could cause diagnostic codes for two injector solenoids.

When an injector is replaced, an injector trim file must be programmed into the ECM. If the ECM is replaced, all injector trim files must be programmed into the new ECM. Refer to Troubleshooting, “Injector Trim File” for more information.

The Caterpillar Electronic Technician (ET) includes the following tests that aid in troubleshooting the injector solenoids:

“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” in order to evaluate the performance of the cylinders that are cut out. As the different cylinders are cut out, a comparison of the change in “Fuel Position” is used to identify cylinders that are weak or misfiring. One reason for a cylinder that is weak or misfiring is an injector that is malfunctioning.

The “Cylinder Cutout Test” can be used to isolate a malfunctioning injector in order to avoid replacement of injectors that are in good condition.

During the test, when a cylinder is cut out, an increase in “Fuel Position” will be noticed for the remaining cylinders. This increase in “Fuel Position” represents an increase in the amount of fuel that must be delivered by the remaining cylinders in order to maintain the desired engine speed.

When a weak cylinder (malfunctioning injector) is cut out, the increase in “Fuel Position” will not be as large as the increase for a cylinder that has an acceptable level of performance.

Note: Prior to running the “Cylinder Cutout Test”, all active diagnostic codes must be repaired.

“Injector Solenoid Test”

Use the “Injector Solenoid Test” to diagnose an open circuit or a short circuit in the wiring for the injector solenoids. With the engine stopped, the “Injector Solenoid Test” will briefly activate each injector solenoid. An audible click can be heard as each solenoid is activated. After performing the test, Cat ET will indicate the status of the solenoid as “OK”, “Open”, or “Short”.

Illustration 1 g03122657
Schematic for the injector solenoids

Illustration 2 g01121683
Left side view

(1) J300/P300 connectors

(2) J2/P2 connectors

Illustration 3 g01099568
P2 terminals that are associated with the injector solenoids

(P2-99) Injector 5 & 6 supply

(P2-104) Injector 1 & 2 supply

(P2-105) Injector 5 return

(P2-106) Injector 3 return

(P2-107) Injector 6 return

(P2-108) Injector 4 return

(P2-115) Injector 3 & 4 supply

(P2-116) Injector 1 return

(P2-118) Injector 2 return

Illustration 4 g01121687
P300 terminals that are associated with the injector solenoids

(P300-1) Injector 1 supply

(P300-2) Injector 2 supply

(P300-3) Injector 3 supply

(P300-4) Injector 4 supply

(P300-5) Injector 5 supply

(P300-6) Injector 6 supply

(P300-13) Injector 6 return

(P300-14) Injector 5 return

(P300-15) Injector 4 return

(P300-16) Injector 3 return

(P300-17) Injector 2 return

(P300-18) Injector 1 return

Table 1
Troubleshooting Test Steps	Values	Results
1. Inspect the Electrical Connectors and the WiringA. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned off. B. Thoroughly inspect connectors (1) and (2). Refer to Troubleshooting, “Electrical Connectors – Inspect”. C. Perform a 45 N (10 lb) pull test on each of the wires that are associated with injector solenoids. D. Check the allen head screw on the ECM connectors for the proper torque. Refer to Troubleshooting, “Electrical Connectors – Inspect” for the proper torque value. E. Check the harness and the wiring for abrasion and for pinch points from the P300 connector to the ECM.	Electrical Connectors and Wiring	Results: The harness and wiring are OK. Proceed to Test Step 2.Results: There is a problem in the connectors and/or wiring. Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem. STOP
2. Check for CodesA. Establish communication between Cat ET and the ECM.	Codes	Results: No diagnostic codes for the injector solenoids are logged. The injector solenoids are operating correctly. There may be a mechanical problem with the injector fuel delivery. Proceed to Test Step 3.Results: A diagnostic code is logged for one or more injector solenoid. There is an electrical problem with an injector solenoid or with the circuit. Proceed to Test Step 4.
3. Perform the “Cylinder Cutout Test”A. Start the engine. B. Allow the engine to warm up to normal operating temperature 77 °C (171 °F). C. Access the “Cylinder Cutout Test”. D. Shut off all parasitic loads such as air compressors which could affect the results of the test. E. Follow the instructions that are given on the screen. F. To start the test, select the start button at the bottom of the screen. G. Use Cat ET to manually cut out the cylinders in order to identify injectors that may have a performance problem. Highlight a cylinder and select the “Change” button at the bottom of the screen. The injector for that cylinder will be disabled. Check for a difference in the sound, feel, or power of the engine. Also, look for a change to the operating parameters that are displayed on the “Cylinder Cutout Test” screen.	Cylinder Cutout Test	Results: The cylinder cutout test indicates that all of the injectors are operating correctly.Repair: If a problem with the fuel system is suspected and diagnostic codes are not active or logged, refer to Systems Operation/Testing and Adjusting for information that is related to the low-pressure fuel system. STOP Results: The cylinder cutout test indicates that at least one of the injectors is not operating correctly. Proceed to Test Step 4.
4. Perform the “Injector Solenoid Test”A. Start the engine. B. Allow the engine to warm up to normal operating temperature 77 °C (171 °F). C. Stop the engine. D. Restore the electrical power to the ECM. E. Access the “Injector Solenoid Test” F. Activate the “Injector Solenoid Test”. G. As each solenoid is energized by the ECM, an audible click can be heard at the valve cover. Allow the “Injector Solenoid Test” to continue until each cylinder is activated at least two times.	Injector Solenoid Test	Results: There is not an electronic problem with the injectors at this time.Repair: he problem appears to be resolved. There may be an intermittent problem in the harness. The problem may have been caused by a poor electrical connection in a connector. If the codes continue to be logged, refer to Troubleshooting, “Electrical Connectors – Inspect”. If the engine is misfiring or if the engine has low power, refer to Troubleshooting, “Engine Misfires, Runs Rough or Is Unstable” or Troubleshooting, “Low Power/Poor or No Response to Throttle”. STOP Results: Note the cylinder that indicates “Open”. Proceed to Test Step 5. Results: Note the cylinder that indicates “Short”. Proceed to Test Step 6.

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

Table 2
Troubleshooting Test Steps	Values	Results
5. Check the Harness between the ECM and the Valve Cover Base for an Open CircuitA. Remove the electrical power from the ECM. B. Disconnect the P300 connector at the valve cover base. C. Restore the electrical power to the ECM. D. Fabricate a jumper wire that will be long enough to short circuit two terminal locations at the P300 connector. Crimp a connector pin to each end of the jumper wire. E. Insert one end of the jumper wire into the P300 connector socket for the suspect injector’s supply wire. Insert the other end of the jumper wire into the P300 connector socket for the suspect injector return wire. This will replace the injector solenoid with a short circuit. F. Perform the “Injector Solenoid Test” at least two times. G. 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	Results: Cat ET displays “Short” for each circuit that was jumpered. The harness between the ECM and the P300 connector does not have an open circuit. Proceed to Test Step 7.Results: Cat ET displays “Open” for the cylinder with the jumper wire. There is a problem in the wiring between the ECM and the P300 connector. There may be a problem with the ECM. Proceed to Test Step 8.

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

Table 3
Troubleshooting Test Steps	Values	Results
6. Check the Harness between the ECM and the Valve Cover Base for a Short CircuitA. Remove the electrical power from the ECM. B. Disconnect the P300 connector. C. Restore the electrical power to the ECM. D. Perform the “Injector Solenoid Test” at least two times.	Short	Results: All cylinders indicate “Open” on Cat ET. The ECM and the engine harness are OK. Proceed to Test Step 7.Results: One or more cylinders indicate “Short” on Cat ET. Note the cylinders that indicate “Short”. Proceed to Test Step 8.

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

Table 4
Troubleshooting Test Steps	Values	Results
7. Check the Injector Harness Under the Valve Cover for an Open Circuit or a Short CircuitA. Remove the electrical power from the ECM. B. Remove the valve cover in order to gain access to the suspect injector. C. Disconnect the harness connector from the suspect injector. D. Thoroughly clean the terminals on the injector solenoid and on the harness connector. E. Use a jumper wire to short circuit the connector terminals for the suspect injector. This will replace the injector solenoid with a short circuit. F. Restore the electrical power to the ECM. G. Perform the “Injector Solenoid Test” at least two times. Note: The injector solenoid that shares the supply wire of the injector that is short circuited may indicate a false test result. Disregard this test result. H. Remove the electrical power from the ECM. I. Remove the jumper wire from the injector connector. This will replace the injector solenoid with an open circuit. J. Restore the electrical power to the ECM. K. Perform the “Injector Solenoid Test” at least two times. L. Remove the electrical power from the ECM.	Open Circuit or a Short Circuit	Results: Cat ET displays the correct status during the test.Repair: The harness wiring is OK. Replace the faulty injector. Verify that the problem is resolved. STOP Results: Cat ET did not display the correct status during the test. Repair: 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. STOP

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

Table 5
Troubleshooting Test Steps	Values	Results
8. Check the ECM for Proper OperationA. Remove the electrical power from the ECM. B. Fabricate a jumper that is long enough to reach from the P2 ECM connector to the engine ground stud. Crimp a connector socket to one end of the jumper wire. C. Disconnect the P2 connector. D. Remove the supply wire from the terminal location for the suspect injector at the ECM connector. Install the jumper wire into this socket. E. Connect the J2/P2 connectors. F. Verify that the ECM will detect an open circuit for the suspect injector: 1. Ensure that the jumper wire is not in contact with a ground source or another circuit. Do not touch the jumper wire during the test. A strong electrical shock hazard is present at the jumper wire while the test is running. 2. Restore the electrical power to the ECM. 3. Perform the “Injector Solenoid Test” at least two times. 4. Remove the electrical power from the ECM. Cat ET displays “Open” for the two injectors that share the supply wire. G. Verify that the ECM detects a short circuit for the suspect injector: 1. Connect the jumper wire to the engine ground stud. Do not touch the jumper wire during the test. A strong electrical shock hazard is present at the jumper wire while the test is running. 2. Restore the electrical power to the ECM. 3. Perform the “Injector Solenoid Test” at least two times. 4. Remove the electrical power from the ECM. Cat ET displays “Short” for the two injectors that share the supply wire.	ECM	Results: The ECM detects the correct status of the circuit.Repair: The ECM is OK. The problem is in the engine harness or in a connector. Inspect the connectors for moisture and for corrosion. Repair the wiring and/or the connector, when possible. Replace parts, if necessary. Clear all diagnostic codes after you complete this test step. STOP Results: The ECM does not detect the correct status of the circuit. Repair: There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, “Replacing the ECM”. Verify that the problem is resolved. STOP

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