853807 1 Mercury BRUSH (Negative)

Background InformationThese engines have Electronic Unit Injectors (EUI) that are electronically controlled. Each injector contains two solenoids. The Engine Control Module (ECM) sends 105 v pulses to each injector solenoid. The pulses are sent at the proper time and at the correct duration for a given engine load and speed.The ECM monitors the current flow through the circuit for each solenoid. If low current flow is detected, a diagnostic code is activated. The ECM continues to try to fire the injector.If high current flow is detected, a diagnostic code is activated. The ECM will disable the solenoid circuit in order to prevent damage from the high current flow. However, the ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the problem is corrected.Typically, problems with an injector solenoid occur when the engine is warmed up and/or when the engine is under vibration (heavy loads). Perform this procedure when the engine is at normal operating temperature. Pay careful attention to the condition of the wiring and the connectors as you perform this procedure. The wiring and/or the connectors may have problems that only occur during vibration.Diagnostic Tests on the Caterpillar Electronic Technician (ET)Cat ET includes the following test that aids in troubleshooting injector solenoids:Injector Solenoid Test - The Injector Solenoid Test identifies an open circuit or a short circuit in the circuits for the injector solenoids. The test is performed while the engine is not running. The "Injector Solenoid Test" briefly activates each solenoid. A good solenoid will create an audible click when the solenoid is activated. Cat ET indicates the status of the solenoid as "OK","Open" or "Short".Note: Refer to the following schematic. Two injector solenoids share a common supply wire. For this reason, an open circuit or a short circuit in a supply wire could cause diagnostic codes for two cylinders.
Illustration 1 g03405336
Table 2
Troubleshooting Test Steps Values Results
1. Check for Logged Codes or Active Codes
A. Establish communication between Cat ET and the ECM . Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Determine if a code is active or logged.
Leakage
Result: There are codes other than an injector code active or logged.
Refer to the appropriate troubleshooting procedure.
Result: A -5 code or a -6 code is logged or active.
Proceed to Test Step 2.
2. Inspect the Wiring Harness Between the ECM and the Valve Cover Base
A. Turn the keyswitch to the OFF position.
B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector. Perform a pull test on each of the wires that are associated with injector solenoids.
D. Check the allen head screw on the ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
E. Check the harness and wiring for abrasions and for pinch points from the valve cover base to the ECM.
Damaged wiring or connectors
Result: The connectors and the wiring appear to be OK.
The harness between the ECM and the connector does not have an open circuit.
Proceed to Test Step 3.
Result: There is a problem with the connectors and/or wiring.
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. Perform an injector solenoid test in order to verify that the problem has been resolved.
3. Check the Harness between the ECM and the Valve Cover Base for an Open Circuit
A. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned off.
B. Remove electrical power from the engine ECM.
C. Disconnect the connectors of the injector harness at the valve cover base.
D. Fabricate a jumper wire long enough to create a short circuit on the different terminal locations at the connector of the injector harness. Crimp connector pins on both ends of the jumper wire.
E. Insert one end of the jumper wire into the connector socket for the suspect injectors supply wire. Insert the other end of the jumper wire into the connector socket for the suspect injectors return wire. The jumper wire will bypass the injector solenoid.
F..Restore electrical power to the engine ECM.
G.Turn the keyswitch to the ON position.
H. Perform the "Injector Solenoid Test" in Cat ET.
I. Repeat this test for each suspect circuit. Stop the "Injector S