C7 and C9 Industrial Engines Troubleshooting – Injection Actuation Pressure Control Valve – Test

Use this procedure to troubleshoot any suspect problems with the Injection Actuation Pressure Control Valve (IAPCV).

This procedure covers the following diagnostic codes:

42-05 Injector Actuation Valve open circuit
42-06 Injector Actuation Valve short to ground

Note: Do not use this procedure to troubleshoot an active 164-11 Injector Actuation Pressure system fault, unless you have been directed to this procedure from another section of this document.

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 Electronic Control Module (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 42-05 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 42-06 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

Illustration 1 g01121315
Schematic for the injection actuation pressure control valve

Illustration 2 g01121264
Left side view

(1) Connector for the IAPCV

(2) J2/P2 connectors

Illustration 3 g01121316
P2 terminations for the IAPCV

(P2-10) Control

(P2-20) Return

Table 1
Troubleshooting Test Steps	Values	Results
1. Inspect the Electrical Connectors and the Wiring A. Turn the keyswitch to the OFF position. 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 the IAPCV. D. Check the allen head screw on the ECM connector for the proper torque. Refer to Troubleshooting, “Electrical Connectors – Inspect”. E. 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.	Electrical Connectors and Wiring	Results: The connectors and the wiring are OK. Proceed to Test Step 2. Results: 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 coupled. Verify that the repair eliminates the problem. STOP
2. Check for Codes A. Connect the Cat^® Electronic Technician (ET) to the service tool connector. B. Observe the “Active Diagnostic” screen on Cat ET. Wait at least 15 seconds so that any codes may become active. Look for these codes: · 42-05 · 42-06	Codes	Results: One of the codes is active. Proceed to Test Step 3. Results: None of the above codes are active. Repair: If any of the above codes are logged and the engine is not running properly, refer to Troubleshooting, “Troubleshooting Without a Diagnostic Code”. If the engine is running properly at this time, there may be an intermittent problem in a harness that is causing the codes to be logged. Refer to Troubleshooting, “Electrical Connectors – Inspect”. STOP
3. Measure the Resistance of the Injection Actuation Pressure Control Valve Solenoid A. Turn the keyswitch to the OFF position. B. Disconnect the J204/P204 connectors. Note: Ensure that the seal on the P204 connector remains on the connector when the connector is disconnected. C. Measure the resistance between terminals P204-1 (Control) and P204-2 (Return) on the IAPCV. Record the value of the resistance measurement	6.5 and 10.5 Ohms.	Results: The resistance measurement is between 6.5 and 10.5 Ohms. Connect the J204/P204 connectors. Proceed to Test Step 4. Results: The resistance measurement is not between 6.5 and 10.5 Ohms. The solenoid resistance is not within the specification. Repair: Replace the unit injector hydraulic pump. Verify that the problem is resolved. STOP
4. Check the Wiring for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the J2/P2 connectors. C. Measure the resistance between terminals J2-10 (Control) and J2-20 (Return).	2 Ohms	Results: The resistance measurement is within two Ohms of the value that was measured in the previous Test Step. Proceed to Test Step 5. Results: The resistance measurement is not within two Ohms of the value that was measured in the previous Test Step. There is a problem with the wiring harness. There may be a problem with a connector. Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the problem is resolved. STOP
5. Check the Wiring for a Short Circuit A. Disconnect the J204/P204 connectors. Note: Ensure that the seal on the P204 connector remains on the connector when the connector is disconnected. B. Disconnect the P1 connector. C. 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.	Resistance	Results: All of the resistance measurements indicate an open circuit. Proceed to Test Step 6. Results: At least one resistance measurement does not indicate an open circuit. There is a problem with a wiring harness. There may be a problem with a connector. Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the problem is resolved. STOP

Table 2
Resistance Measurements for the Wiring Harness
Connector and Terminal	Terminal
P2-10 (Control)	All of the other terminals on the P2 connector
	All of the terminals on the P1 connector
	Engine ground
P2-20 (Return)	All of the other terminals on the P2 connector
	All of the terminals on the P1 connector
	Engine ground

Table 3
Troubleshooting Test Steps	Values	Results
6. Check the ECM by Cranking the Engine A. Verify that the J204/P204 connectors are disconnected. Note: Do not insert any wire that is larger than 18 AWG into the J204 harness connector. 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. B. Insert a Deutsch connector pin into each socket of the J204 harness connector. C. Connect a voltage test lamp to the connector pins that are inserted in the J204 connector. Crank the engine and observe the test lamp.	Test lamp	Results: The voltage test lamp illuminates when the engine is cranking. Remove the connector pins from the P204 connector. Connect all of the electrical connectors. Clear any diagnostic codes. Proceed to Test Step 7. Results: The voltage test lamp does not illuminate when the engine is cranking. Repair: Replace the ECM. Refer to Troubleshooting, “Replacing the ECM”. STOP
7. Perform the “Injection Actuation Pressure Test” A. Disconnect the J204/P204 connectors. B. Crank the engine three times at 30 seconds intervals. This will purge the air from the system. C. Connect the J204/P204 connectors. D. Start the engine. E. 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”. F. After performing the “Injection Actuation Pressure Test”, check for the following active diagnostic codes: · 42-05 · 42-06	Codes	Results: The problem appears to be resolved. The original problem was probably caused by a poor electrical connection. STOP Results: There is a problem with the IAPCV. Repair: Replace the unit injector hydraulic pump. Verify that the problem is resolved. STOP

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