910K, 910M, 914K, 914M, 918M, and 920K Wheel Loaders Machine Electronic Control System Caterpillar

General Information

Usage:

920K B98

The diagnostics for the electronic control module (ECM) can be accessed through the Cat^® Monitoring System or Cat^® Electronic Technician (Cat ET). Troubleshooting a system will require additional information from other machine service manuals. In addition to the Troubleshooting Manual, each machine comes with the following manuals:

Operator and Maintenance Manual
Disassembly and Assembly
Systems Operations
Testing and Adjusting
Specifications
Hydraulic Schematic
Electrical Schematic

Other types of literature applicable to the machines such as Service Letters and Special Instructions are also available.

To access the manuals, go to SIS web (https://sis.cat.com) and enter the serial number prefix for the machine into the "Serial Number or Prefix" field on the web page.
Note: The serial number prefixes for the applicable machines are listed on the cover of this manual.
Then select "Documentation". All of the literature available to that machine will be listed.

As a guide, a simplified system schematic is included at the end of this manual. For an accurate representation of the machine that is being diagnosed, refer to the electrical system schematic for the machine being serviced.

When the troubleshooting procedure instructs you to “REPAIR THE HARNESS OR REPLACE 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 in order 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. The power circuits of the ECM should have less than 2 ohms of resistance between the contacts of the ground connector and the frame ground. Less than 5 ohms of resistance is required for signal circuits for normal operation. 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.

Failure of an electrical component can cause the failure of other components. Also, failure of an electrical component can be caused by the failure of other components. Always attempt to correct the cause of an electrical system failure before you replace a component.