The injection actuation pressure control valve (IAPCV) that is internal to the unit injector hydraulic pump 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 Electronic Control Module (ECM). The variable displacement unit injector hydraulic pump pressurizes only the amount of high pressure oil that is needed.
The ECM performance maps contain 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.
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| Illustration 1 | g00955788 |
Location of the IAPCV (typical example) | |
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| Illustration 2 | g01158010 |
Schematic | |
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| Illustration 3 | g01158018 |
ECM connector P2 | |
The following information is provided in order to better help the technician troubleshoot the system.
42-05 - This code indicates that there is an open in the supply line and/or that there is a short to ground in the return line to the IAPCV. The ECM detects a low current in the circuit.
42-06 - This code indicates that there is an external short to the +Battery in either the supply line or the return line to the IAPCV. There is also the possibility that the supply line is shorted to the engine ground. The ECM detects a high current in the circuit. The ECM latches both circuit drivers in the open position in order to prevent damage to the circuit.
42-07 - This code indicates that the injection actuation pressure is not being controlled properly. There may be incorrect fluctuations in the amount of current flow.
42-08 - This code indicates that there is a short between the supply and the return line to the IAPCV. The short could be in wiring of the circuit or in the IAPCV. The ECM initially detects a high current. The ECM then detects a low current.
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Test Step 1. Inspect Electrical Connectors and Wiring
- Turn the keyswitch to the OFF position.
- Thoroughly inspect the J500/P500 connector for the IAPCV and inspect the J2/P2 ECM connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the IAPCV (J2/P2:61 and J2/P2:62).
- Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
- Check the harness and wiring for abrasion and pinch points from the sensors 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 and the harness and wiring are free of corrosion, of abrasion, and of pinch points.
Results:
- OK - The connectors and the harness wiring are okay. Proceed to Test Step 5.
- Not OK - The connectors or the wiring are damaged.
Repair: Perform the following 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 the Current to the IAPCV
- Install a 224-9282 Adapter Cable As (Test) (Current) in series with the P500 connector. Reconnect the J500/P500 connector.
- Connect an ammeter in series with the adapter cable. Set the multimeter on the lowest current range that is greater than one amp.
- Turn the keyswitch to the START position.
- Crank the engine and record the following data:
________ Current reading from the ammeter
- Turn the keyswitch to the OFF position.
- Remove the 224-9282 Adapter Cable As (Test) (Current) that is in series with the P500 connector. Reconnect the J500/P500 connector.
Expected Result:
The current is greater than 250 mA.
Results:
- OK - The current is greater than 250 mA.
Repair: The system is operating correctly.
STOP
- Not OK - The current is less than 250 mA. Proceed to Test Step 3.
Test Step 3. Measure the Solenoid Resistance of the IAPCV
- Disconnect the J500/P500 connector for the IAPCV.
Note: Ensure that the seal on the connector "P500" remains on the connector "P500" when the connector is disconnected.
- Use a multimeter to measure the resistance between J500:1 and J500:2 of the IAPCV. Record the value that was measured.
________ Resistance reading from the multimeter
- Use a multimeter to measure the resistance between J500:1 and engine ground. Use a multimeter to measure the resistance between J500:2 and engine ground. Record the value that was measured.
________ Resistance reading from the multimeter J500:1
________ Resistance reading from the multimeter J500:2
- Reconnect the J500/P500 connector for the IAPCV.
Expected Result:
The solenoid resistance of the IAPCV is between 6 and 11 Ohms. The resistance between J500:1 and J500:2 and engine ground is greater than 20,000 Ohms.
Results:
- OK - The solenoid resistance of the IAPCV is between 6 and 11 Ohms. The resistance between J500:1 and J500:2 and engine ground is greater than 20,000 Ohms. Proceed to Test Step 4.
- Not OK - The resistance was not within the specification.
Repair: Replace the HEUI pump. Verify that the repair eliminates the problem.After the HEUI pump has been replaced, the engine may need to be cranked for a significant length of time in order to fill the pump with oil. Clear any faults or events that activated during the initial start-up. Retest the system.
STOP
Test Step 4. Measure the Solenoid Resistance through the Engine Harness
- Disconnect the J2/P2 ECM connector.
- Use a multimeter to measure the resistance between P2:61 and P2:62 at ECM connector P2. Record the value that was measured.
________ Resistance reading from the multimeter
- Check the resistance from P2:61 to the engine ground stud and from P2:62 to the engine ground stud. The resistance should be greater than 20,000 ohms. Record the value that was measured.
________ Resistance reading from the multimeter P2:61
________ Resistance reading from the multimeter P2:62
- Check the resistance from P2:61 to the +Battery terminals P1:52 and P1:53. Check the resistance from P2:61 to the +Battery terminals P1:52 and P1:53. The resistance should be greater than 20,000 ohms.
________ Resistance reading from the multimeter P2:61
________ Resistance reading from the multimeter P2:62
Expected Result:
The resistance measurements are within the proper range.
Results:
- OK - The resistance measurements are within the proper range. Proceed to Test Step 5.
- Not OK - The resistance measurements are outside of the proper range.
Repair: Replace the harness for the IAPCV.
STOP
Test Step 5. Check the Current to the Injection Actuation Pressure Control Valve (IAPCV)
- Install a 224-9282 Adapter Cable As (Test) (Current) in series with the P500 connector. Reconnect the J500/P500 connector.
- Connect an ammeter in series with the adapter cable. Set the multimeter on the lowest current range that is greater than one amp.
- Turn the keyswitch to the START position.
- Crank the engine and record the following data:
________ Current reading from the ammeter
- Turn the keyswitch to the OFF position.
- Remove the 224-9282 Adapter Cable As (Test) (Current) that is in series with the P500 connector. Reconnect the J500/P500 connector.
Expected Result:
The current is greater than 250 mA.
Results:
- OK - The current is greater than 250 mA.
Repair: The system is operating correctly.
STOP
- Not OK - The current is less than 250 mA.
Repair: Replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".
STOP