15781A 5 Mercury FUEL CONNECTOR

Table 1
Diagnostic Codes Table
Code and 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 code is logged.
The ECM will illuminate the check engine lamp. The ECM will pulse the action lamp and the action alarm at a rate of .5 Hz per second.
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 ECM will illuminate the check engine lamp. The ECM will pulse the action lamp and the action alarm at a rate of .5 Hz per second. 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 wireThe 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
Illustration 1 g01337725
Schematic for the injection actuation pressure control valve
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Illustration 2 g01709933
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".
Illustration 3 g01339387
Terminal locations at the P2 ECM connectors for the IAPCV
(P2-10) Return
(P2-20) Injection actuation pressure control valve
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.STOPTest 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 05 or 06. 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.STOPTest 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.STOPTest 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