RADIO GP 3971505 - Caterpillar

Introduction
ReferenceSystems Operation, Troubleshooting, Testing and Adjusting, KENR9023, "793F and 797F Off-Highway Truck/ Tractors VIMS Monitoring and Payload"ReferenceTroubleshooting Testing and Adjusting, RENR2631, "784C, 785B, 785C, 785D, 789B, 789C, 793B, 793C, 793D, 797 and 797B Off-Highway Truck/Tractors Vital Information Management System (VIMSTM)"ReferenceSystems Operation, Troubleshooting, Testing and Adjusting, RENR8386, "773D and 777D Off-Highway Truck Payload Measurement System (TPMS)"ReferenceSystems Operation, Troubleshooting, Testing and Adjusting, RENR8284, "770, 772, 773F and 777F Off-Highway Truck/Tractors and 775F Quarry Truck VIMS Truck Payload System"The Truck Payload Measurement System (TPMS) does not always perform properly on Off-Highway Trucks due to issues with the measurement of suspension cylinder (strut) pressures and suspension cylinder pressure sensors. This Technical Information Bulletin relates only to truck models equipped with the TPMS and using suspension cylinder 221-3416 Pressure Sensor Gp and/or 221-3417 Pressure Sensor Gp . The problem that is identified below does not have a known permanent solution. Until a permanent situation is known, use the solution that is identified below. Problem
Troubleshooting of suspension cylinder pressure sensors frequently results in the replacement of a properly functioning sensor. Laboratory analysis of returned sensors concludes if a sensor is producing a frequency output at the signal pin, then the pressure sensor will likely operate as specified throughout the required pressure range. Also, sensors are likely to be replaced when other conditions such as leaking suspension cylinders or defective check valve core/poppets are present. Replacing a good sensor may temporarily mask the actual problem and lead to additional truck downtime in the future.Solution
Ensure that the following steps are followed as directed in the above referenced publications:
Review the section on sensor output frequency testing and follow the section closely. Ensure that a signal frequency test is properly performed when directed in the troubleshooting process.
Monitor other conditions that may generate pressure sensor (suspension cylinder) diagnostics. Such examples are defective check valve core/poppet, leaking suspension cylinders, and defective sensor harnesses due to physical or water damage.
Refer to the appropriate Off-Highway Truck/Tractor Electronic Control System Troubleshooting Manual for specific troubleshooting information on suspension cylinder pressure sensor diagnostic codes. When troubleshooting an active CID 838, CID 839, CID 840, or CID 841 diagnostic code, perform the following procedure:
Perform the signal frequency test as directed in the Troubleshooting manual.
Inspect the suspension cylinder assemblies to ensure that no other problems are negatively affecting the operation of the pressure sensor (suspension cylinder). Inspect for leaking or damaged suspension cylinders.
Inspect the electrical pin and socket contacts for the pressure sensor harness connections for the presence of water, corrosion, or debris within the connector. If any are found, thoroughly clean or replace the contact as needed.
Ensure the harness electrical connectors to the suspension cylinder pressure sensor are seated completely into the mating electrical connectors on the truck harness. Ensure that the locking tabs on the connectors are latched.
If the sensor is found to be the root cause, provide a detailed account of the troubleshooting process. Include diagnostics codes present, screen capture of Caterpillar Electronic Technician (Cat ET) screen, model of electrical meter used