Use this procedure to troubleshoot any suspect problems with the Injection Actuation Pressure Control Valve (IAPCV). Use this procedure if one of the diagnostic codes in Table 1 is active or easily repeated.
| Diagnostic Codes Table | ||
|---|---|---|
| Description | Conditions which Generate this Code | System Response |
| 42-5 Injector Actuation Valve current below normal | The Electronic Control Module (ECM) detects a current in the circuit for the IAPCV that is below the minimum threshold. | The engine may begin to misfire and/or shutdown. The engine may experience reduced speed (rpm) and/or low power.
The ECM will trigger a snapshot. The code is logged. |
| 42-6 Injector Actuation Valve current above normal | The ECM detects a current in the circuit for the IAPCV that is above the maximum threshold. | The engine may begin to misfire and/or shutdown. The engine may experience reduced speed (rpm) and/or low power.
The ECM will trigger a snapshot. The code is logged. |
The IAPCV is internal to the unit injector hydraulic pump. The IAPCV is a precision displacement control actuator. This actuator changes the pump outlet flow that is based on the control current that is supplied by the ECM. The variable displacement unit injector hydraulic pump pressurizes only the amount of high pressure oil that is needed.
The ECM software contains performance maps. The performance maps have a desired actuation pressure for every engine operating condition. The ECM sends a control current to the IAPCV. This signal creates an actual actuation pressure that matches the desired actuation pressure. If the actual actuation pressure does not match the desired actuation pressure, the ECM will increase the control current or the ECM will decrease the control current to the IAPCV in order to adjust pump outlet flow.
The following problems can cause a -5 diagnostic code:
- An open circuit in the wiring
- An open circuit in the IAPCV
- A short to ground on the return wire
The following problems can cause a -6 diagnostic code:
- The control wire has a short to the +Battery.
- The return wire has a short to the +Battery.
- A short circuit in the IAPCV
- A short to ground on the control wire
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| Illustration 1 | g01337725 |
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Schematic for the injection actuation pressure control valve | |
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The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere. |
Test Step 1. Inspect the Electrical Connectors and the Wiring
- Remove the electrical power from the ECM.
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Illustration 2 g01388298 Component locations for the IAPCV (Typical left side engine view)
(1) Connector for the injection actuation pressure control valve
(2) J2/P2 ECM connectors - Thoroughly inspect connectors (1) and (2). Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
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Illustration 3 g01339387 Terminal locations at the P2 ECM connectors for the IAPCV
(P2-10) Return
(P2-20) Injection actuation pressure control valveShow/hide table
Illustration 4 g01218763 Terminal locations at the connector for the IAPCV
(1) Injection actuation pressure control valve
(2) Return - Perform a
45 N (10 lb) pull test on each of the wires that are associated with the IAPCV. - Check the torque of the allen head screws for each of the ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
- Check the harness and wiring for abrasion and for pinch points from the IAPCV back to the ECM.
Note: Ensure that the seal is installed on the harness connector for the injection actuation pressure control valve.
Expected Result:
All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.
Results:
- OK - The connectors and the wiring are OK. Proceed to Test Step 2.
- Not OK - There is a problem with the connectors and/or the 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
Test Step 2. Check for Active Diagnostic Codes
- Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
- Restore the electrical power to the ECM.
- Start the engine.
- Observe the "Active Diagnostic" screen on Cat ET. Wait at least 30 seconds so that any codes may become active. Look for the code that is -5 or -6.
Expected Result:
One of the above codes is active.
Results:
- Active code - One of the above codes is active. There is a problem in the electrical circuit for the IAPCV. Proceed to Test Step 3.
- No active codes - Neither of the above codes are active.
Repair: If one of the above codes is logged and the engine is not running properly, refer to Troubleshooting, "Symptom Troubleshooting".
If the engine is running properly at this time, there may be an intermittent problem in a harness or in an electrical connector that is causing the codes to be logged. Refer to Troubleshooting, "Electrical Connectors - Inspect" for information that is related to troubleshooting intermittent electrical problems.
STOP
Test Step 3. Measure the Resistance of the Injection Actuation Pressure Control Valve's Solenoid
- Remove the electrical power from the ECM.
- Disconnect the connectors for the IAPCV at the injection pump.
Note: Ensure that the seal on the connector for the IAPCV remains on the connector when the connector is disconnected.
- Measure the resistance between terminals 1 on the IAPCV. Record the value of the resistance measurement.
Expected Result:
The resistance measurement is between 6.5 and 10.5 Ohms.
Results:
- OK - The resistance measurement is between 6.5 and 10.5 Ohms. The IAPCV appears to be OK. Connect the connectors for the IAPCV. Proceed to Test Step 4.
- Not OK - The resistance measurement is not between 6.5 and 10.5 Ohms. The solenoid's resistance is not within the specification.
Repair: Replace the unit injector hydraulic pump. Verify that the problem is resolved.
STOP
Test Step 4. Check the Harness for an Open Circuit
- Remove the electrical power from the ECM.
- Disconnect the J2/P2 connectors.
- Measure the resistance between terminal locations P2-20 and P2-10 at the ECM connector.
Expected Result:
The resistance measurement is within two Ohms of the value that was measured in the previous Test Step.
Results:
- OK - The resistance measurement is within two Ohms of the value that was measured in the previous Test Step. The harness appears to be OK. Proceed to Test Step 5.
- Not OK - The resistance measurement is not within two Ohms of the value that was measured in the previous Test Step.
Repair: There is a problem in the wiring harness or in a connector. Repair the harness and/or the connector, when possible. Replace parts, if necessary. Verify that the original problem is resolved.
STOP
Test Step 5. Check the Harness for a Short Circuit
- Disconnect the connectors for the IAPCV at the injection pump.
Note: Ensure that the seal on the connector for the IAPCV remains on the connector when the connector is disconnected.
- Disconnect the P1 connector.
- Measure the resistance between the points that are listed in Table 2. Be sure to wiggle the wires in the harnesses as you make each resistance measurement.
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Table 2 Resistance Measurements for the Wiring Harness Connector and Terminal Terminal P2-20 (Injection actuation pressure control valve) All of the other terminals on the P2 connector All of the terminals on the P1 connector Engine ground stud P2-10 (Return) All of the other terminals on the P2 connector All of the terminals on the P1 connector Engine ground stud
Expected Result:
All of the resistance measurements indicate an open circuit.
Results:
- OK - All of the resistance measurements indicate an open circuit. The harness appears to be OK. Proceed to Test Step 6.
- Not OK - At least one resistance measurement does not indicate an open circuit.
Repair: There is a problem with a wiring harness and/or in a connector. Repair the wiring and/or the connector, when possible. Replace parts, if necessary. Verify that the original problem is resolved.
STOP
Test Step 6. Check the ECM by Cranking the Engine
- Verify that the connectors for the IAPCV have been disconnected at the injection pump.
Note: Do not insert any wire that is larger than 18 AWG into the harness connector for the IAPCV. Do not insert the probe for the voltage test lamp into the harness connector. These actions will spread the sockets of the connector which will damage the connector. Damaged connectors could cause intermittent connections.
- Insert a connector pin into each socket of the harness connector for the IAPCV at the injection pump.
- Connect a voltage test lamp to the connector pins that are inserted in the connector for the IAPCV. Crank the engine and observe the test lamp.
Note: This Test Step may activate additional diagnostic codes. Ignore the codes and monitor the test lamp. Clear the codes at the end of the Test Step.
Expected Result:
The voltage test lamp illuminates when the engine is cranking.
Results:
- OK - The voltage test lamp illuminates when the engine is cranking. Remove the connector pins from the IAPCV connector. Connect all of the electrical connectors. Clear any diagnostic codes. Proceed to Test Step 7.
- Not OK - The voltage test lamp does not illuminate when the engine is cranking.
Repair: There is a problem with the ECM. Perform the following procedure:
- Temporarily connect a test ECM.
Refer to Troubleshooting, "ECM - Replace".
- Recheck the circuit in order to ensure that the original problem has been resolved.
If the problem is resolved with the test ECM, install the suspect ECM. If the problem returns with the suspect ECM, replace the ECM. Verify that the problem is resolved.
If the problem is not resolved with the test ECM, install the original ECM. There is a problem in the wiring.
STOP
- Temporarily connect a test ECM.
Test Step 7. Perform the "Injection Actuation Pressure Test"
- Disconnect the connectors for the IAPCV at the injection pump.
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NOTICE Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.
- Crank the engine three times at 30 seconds intervals. This will purge the air from the system.
- Connect the connectors for the IAPCV.
- Start the engine.
- Run the "Injection Actuation Pressure Test". The "Injection Actuation Pressure Test" is located in the "Diagnostics" menu on Cat ET. Step through all of the pressure ranges.
Note: This is not the "Injection Act Press Driver Test".
- After performing the "Injection Actuation Pressure Test", check for the following active diagnostic codes:
- -5
- -6
Expected Result:
The test is successful. There are no diagnostic codes.
Results:
- OK - The problem appears to be resolved.
Repair: The original problem was probably caused by a poor electrical connection.
STOP
- Not OK - One or both of the diagnostic codes is active.
Repair: There is a problem with the injection actuation pressure control valve. Replace the unit injector hydraulic pump. Verify that the problem is resolved.
STOP