320C and 322C Excavators Attachment Hydraulic System – General Information

Troubleshooting the electronic control system will require additional information from the Service Manual of the machine. The reference material should be consulted: the Electrical System Schematic, the Parts Manual and the Operation And Maintenance Manual. As a reference, a typical system schematic is included at the end of this manual. For an accurate representation of the machine that is being diagnosed, see the Testing And Adjusting, “System Schematic”. You should use the Electrical System Schematic in the Service Manual of the machine in order to trace the circuit, if a troubleshooting procedure instructs you to “REPAIR THE HARNESS”. The continuity checks and resistance checks should be performed at the connectors in order to locate a failure in the harness. At a component connector, always check the ground circuit. Less than five ohms of resistance is required from the ground contacts to frame ground. A problem can be incorrectly diagnosed, if an excessive resistance that is greater than 5 ohms is present in the ground circuit. During a troubleshooting procedure, you should inspect all component and harness connections before a component is replaced. If these connections are not clean and tight, the connection can cause an electrical problem. The problem can be permanent or the problem can be intermittent. Ensure that the wires are pushed into the connectors completely. Make sure that the connections are tight before other tests are performed. A failure of an electrical component can cause a failure of another component or a failure can be caused by the failure of other components. You should always attempt to find a failure and you should correct the cause of a failure in the electrical system before you replace a component.