The diagnostics for the electronic control module (ECM) can be accessed through the Cat® Monitoring System or the Cat® Electronic Technician (Cat ET). Troubleshooting a system requires additional information from the service manual for the machine. The additional manuals that may be required are listed below.
- Specifications, UENR4598, "844K Wheel Dozer (T4F & LRC) Machine Systems Specifications "
- Systems Operation/Testing And Adjusting, UENR4599, "844K Wheel Dozer (T4F & LRC) Machine Systems Operation/Testing & Adjusting"
- System Operation , KENR6489, "988K/990K/824K/825K/826K/834K/836K/844K Monitoring System".
- OMM, SEBU9122, "844K Wheel Dozer (T4F & LRC)"
- Hydraulic Schematic, UENR4895, "844K Wheel Dozer (T4F & LRC) Hydraulic System Schematic"
- Electrical Schematic, UENR4996, "844K Wheel Dozer (T4F) Electrical System Schematic" .
- Electrical Schematic, UENR1697, "844K Wheel Dozer (LRC) Electrical System Schematic" .
The troubleshooting procedure may instruct you to “REPAIR THE HARNESS”. Use the electrical system schematic for the machine that is being serviced to trace the circuit.
Perform continuity checks at the harness connectors to locate harness failures.
At the connectors of the components, always check the ground circuit. Less than 5 ohms of resistance is required between the ground contacts of the connector and the frame ground. Excessive ground resistance that is greater than 5 ohms can cause incorrect diagnosing of problems.
During troubleshooting, inspect all connections before any component is replaced. If these connections are not clean and tight, permanent electrical problems or intermittent electrical problems can result. Check that the wires are pushed into the connectors completely. Make sure that the connections are tight before other tests are made.
When you perform wiring harness tests, do not puncture the wire insulation. Use test leads such as the 7X-1710 Multimeter Probe to troubleshoot the harness without damaging the wire insulation.
If damaged wire insulation is found during troubleshooting, repair the damage. Seal the damaged wires with 8T-0065 RTV Silicone Sealant. Cover the sealant with two layers of 1P-0810 Tape.
Failure of an electrical component can cause the failure of other components. Always attempt to correct the cause of an electrical system failure before you replace a component.
When you are removing the machine harness from the ECM, use the single screw in the center of the harness connector.
Refer to the following warnings and the notice for all inspections and tests of the power train. If the source of the problem is not determined, perform the inspections and tests. Perform the inspections and tests in sequential order. For all tests, the power train oil must be at normal operating temperature.
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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the power train. |
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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand. |
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Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak. |
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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates. |
Note: This machine is equipped with a Transmission ECM. The Transmission ECM is equipped with built-in diagnostics that detect faults in the electronic system of the power train.
- Use the built-in electrical diagnostics that are performed through the Transmission ECM to check for any active service codes for the Transmission ECM.
- Perform visual checks. If the visual checks are completed but the problem has not been identified, perform operational checks. If the problem is not understood, perform instrument tests. This procedure will help to identify power train problems.
- There may be more than one cause for a problem. The Troubleshooting section of this manual may suggest specific inspections or specific instrument tests that should be performed.
Note: The inspections and the tests that are found in the reference literature will help to identify the most probable causes of a problem. The reference literature cannot include all of the possible problems and all of the corrections. The service personnel must find the problem and the source of the problem. Then, the necessary repairs can be made.