0125460 JOHNSON HOUSING

Overview
These engines are equipped with an electronic control system. The system consists of a computer, sensors, and software. The system performs these functions:
Control of the engine
Control of the Selective Catalyst Reduction (SCR) system
Control of particulate emissions via the Clean Emission Module (CEM)
Applications control system interface
Fault detection and reportingElectronic Control System
The Electronic Control Module (ECM) is a computer that controls the operation of the engine.The ECM contains a flash file. The flash file is the software for the ECM. The flash file contains the operating maps. The operating maps define the following characteristics of the engine:
Horsepower
Torque curves
Engine speed (rpm)Refer to Troubleshooting, "System Overview" for additional information on the electronic control system.Application Interface
The ECM interfaces with the machine via software and an electrical connector on the ECM. The software can be configured.The application control system provides inputs to the electrical connector on the ECM in order to indicate the status of switches. Correctly configure the ECM in order to interpret the inputs.The ECM provides outputs for the application control system via the electrical connector in order to control lamps, solenoids, and other devices. Correctly configure the ECM in order for the outputs to match the configuration of the application control system.Clean Emissions Module (CEM)
The CEM contains these components:Diesel Particulate Filter (DPF) - A DPF is installed in the exhaust system. The DPF collects soot and ash from the engine exhaust.Diesel Oxidation Catalyst (DOC) - A DOC is installed in the exhaust system. The DOC oxidizes hydrocarbons (HC), carbon monoxide (CO), odor causing compounds, and soluble organic fractions (SOF).Selective Catalyst Reduction (SCR) System - The SCR system is used to reduce NOx emissions from the engine. The SCR system is installed after the DPF in the exhaust.Fault Detection and Reporting
The ECM monitors inputs from the sensors and inputs from the applications control system. Software in the ECM interprets the inputs. The software determines if the inputs are operating correctly. A diagnostic trouble code is activated when the software detects a problem with an input.The ECM broadcasts the codes on two data links. The data links are the Cat Data Link (CDL) and J1939. Caterpillar Electronic Technician (ET) must communicate on both data links in order to service the engine. If a problem is suspected with one of the data links, refer to Troubleshooting, "Data Link - Test".The codes can be displayed on Cat ET and optional operator interfaces. Refer to Troubleshooting, "Diagnostic Trouble Codes" for additional information on diagnostic trouble codes and a complete list of codes.Troubleshooting
As a reference, simplified schematics for each of the engine subsystems are included with each of the circuit tests that are in this manual. For an accurate representation of the entire electrical schematic that is for your application, refer to the Electrical System Schematic.During troubleshooting, inspect all harness connections before any component is replaced. If these connections are not clean and tight, continuous 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 may cause the failure of other components. Always attempt to correct the cause of an electrical failure before you replace a component. If wire insulation is punctured, repair the damage. Seal the damaged wires with 8T-0065 Silicone Sealant. Cover the sealant with two layers of 1P-0810 Electrical Tape.Troubleshooting Associated CodesCertain systems will display multiple codes for troubleshooting . These "Associated Codes" must be used in order to troubleshoot the system. The codes should be viewed as separate levels of troubleshooting. For example, a "High DPF #1 Soot Loading" code is generated if the engine is allowed to run after a regeneration warning is displayed. This main code is not the code that requires troubleshooting.The system is designed to display the codes for this separate level of troubleshooting as an "Associated Code". The "Associated Code" is the diagnostic or the event code that needs to have the troubleshooting procedure followed.The following paragraph is an example of troubleshooting the engine system with "Associated Codes".After connecting Cat ET to an engine, the following codes are displayed:
High DPF #1 Soot Loading
Aftertreatment Insufficient Temperature to Complete Regeneration
Aftertreatment Fuel Injector #1 not respondingThese codes are the result of a fouled nozzle. The regeneration system was unable to increase the exhaust gas temperature enough to regenerate the trap because the fittings or the nozzle failed. The "High DPF #1 Soot Loading" code was generated because the trap was unable to regenerate. The troubleshooting procedure to use in this case is the "Aftertreatment Fuel Injector #1 not responding" code, which will fix the other two issues.