The standard instrument cluster has a diagnostic LED and alarm. The optional instrument cluster has diagnostic display screens. When there is a problem with the system there will be some operational symptom that will be present.
On machines equipped with the standard instrument cluster, Caterpillar ET must be used in order to access any diagnostic and event information.
On machines equipped with the optional instrument cluster, diagnostic and event information can be accessed either through Caterpillar ET or through the instrument cluster itself.
Troubleshooting the ECM may require additional information from the machine Service Manual. The following items may be required.
- Electrical System Schematic
- Parts Manual
- Operation and Maintenance Manual
As a guide, a simplified system schematic is at the end of this manual. For a complete electrical system schematic, see the Electrical System Schematic in the machine Service Manual.
When the troubleshooting procedure instructs you to REPAIR THE HARNESS, use the Electrical System Schematic in the machine Service Manual in order to trace the circuit. Perform continuity checks at the connectors in order to locate harness failures. At component connectors, always check the ground circuit. Less than 5 ohms of resistance is required between the connector ground contacts and frame ground. Resistance that is greater than 5 ohms can cause an incorrect diagnosis of problems.
During troubleshooting, inspect all component and harness connections before any component is replaced. If these connections are not clean and tight the connections can cause electrical problems. The problems may be permanent or intermittent. Check that the wires are pushed into the connectors completely. Make sure that the connections are tight before any other tests are made.
Repairs of the machine harness should be performed with the wire of the same size. All joints should be soldered. All joints should be tightly taped or all joints should be covered with shrink sleeving. Use 1P-0810 Electrical Tape .
Failure of an electrical component can cause the failure of one or more components. Always attempt to find the cause of a problem and correct the problem before replacing a component.
The A5:M12 Machine ECM uses a new Deutsch DRCP-Series 80/86-pin connector. Refer to Special Instruction, REHS7852 for complete service information on the new connector.
The Engine ECU uses a Molex MXD-Series 80 pin connector. Refer to Special Instruction, REHS7297 for complete service information on the new connector.