855860 Volvo.Penta Servo pump

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.
Determine If The Problem Is Intermittent. If the problem is intermittent, attempt to test the circuit before you disconnect any electrical connectors. This helps identify the root cause of intermittent problems.The "Wiggle Test" on the Caterpillar Electronic Technician (ET) may be able to test the circuit. Refer to the documentation that accompanies Cat ET.Perform the wiggle test on the circuit, when possible. Otherwise, continue with this procedure.
Check the Connectors for Moisture and For Corrosion.
Illustration 1 g01131211
Leaky seal at the connector (typical example)
Inspect all wiring harnesses. Ensure that the routing of the wiring harness allows the wires to enter the face of each connector at a perpendicular angle. Otherwise, the wire will deform the seal bore. Refer to Illustration 1. This will create a path for the entrance of moisture. Verify that the seals for the wires are sealing correctly.
Illustration 2 g01131276
Diagram for the installation of a connector plug (typical example)
(1) Electronic Control Module (ECM) connector
(2) Correctly inserted plug
(3) Incorrectly inserted plug
Ensure that the sealing plugs are in place. If any of the plugs are missing, replace the plug. Ensure that the plugs are inserted correctly into the connector. Refer to Illustration 2.
Illustration 3 g01131019
Seal for a three-pin connector (typical example)
Illustration 4 g01131165
Seal for ECM connector (typical example)
Disconnect the suspect connector and inspect the connector seal. Ensure that the seals are in good condition. If necessary, replace the connector.
Thoroughly inspect the connectors for evidence of moisture entry. Note: It is normal to see some minor seal abrasion on connector seals. Minor seal abrasion will not allow the entry of moisture.If moisture or corrosion is evident in the connector, the source of the moisture entry must be found and the source of the moisture entry must be repaired. If the source of the moisture entry is not repaired, the problem will recur. Simply drying the connector will not fix the problem. Check the following items for the possible moisture entry path:
Missing seals
Improperly installed seals
Nicks in exposed insulation
Improperly mated connectorsMoisture can also travel to a connector through the inside of a wire. If moisture is found in a connector, thoroughly check the connector's harness for damage. Also check other connectors that share the harness for moisture.Note: The ECM is a sealed unit. If moisture is found in an ECM connector, the ECM is not the source of the moisture. Do not replace the ECM.
Check the Wires for Damage to the Insulation.
Carefully inspect each wire for signs of abrasion, of nicks, and of cuts. Inspect the wires for the following conditions:
Exposed insulation
Rubbing of a wire against the engine
Rubbing of a wire against a sharp point
Check all of the wiring harness fasteners in order to verify that the harness is properly secured. Also check all of the fasteners in order to verify that the harness is not compressed. Pull back the harness sleeves in order to check for a flattened portion of wire. A fastener that has been overtightened flattens the harness. This damages the wires that are inside the harness.
Inspect the Connector Terminals. Visually inspect each terminal in the connector. Verify that the terminals are not damaged. Verify that the terminals are properly aligned in the connector and verify that the terminals are properly located in the connector.
Perform a Pull Test on Each Wire Terminal Connection.
Illustration 5 g01131435
Receptacle lock wedge (typical example)
Ensure that the locking wedge for the connector is installed properly. Terminals cannot be retained inside the connector if the locking wedge is not installed properly.
Perform the 45 N (10 lb) pull test on each wire. Each terminal and each connector should easily withstand 45 N (10 lb) of tension and each wire should remain in the connector body. This test checks whether the wire was properly crimped in the terminal and whether the terminal was properly inserted into the connector.
Check Individual Pin Retention into the Socket.
Illustration 6 g01131604
Diagram for testing pin retention (typical example)
Verify that the sockets provide good retention for the pins. Insert a new pin into each socket one at a time in order to check for a good grip on the pin by the socket.
Check the Locking Mechanism of the Connectors.
Ensure that the connectors lock properly. After locking the connectors, ensure that the two halves cannot be pulled apart.
Verify that the latch tab of th