0336448 JOHNSON BAFFLE, Exhaust hsg.

Active Diagnostic Codes
An Active diagnostic code represents a problem with the electronic control system that is happening now. It should be investigated and corrected as soon as possible.When an active diagnostic code is generated, the Check Engine Lamp will produce a visible warning. The Check Engine Lamp is located on the Diagnostic Enable Switch. The Diagnostic Enable Switch is located behind the electrical panel door outside the cab. Open the panel door and look towards the bottom to locate the Check Engine Lamp and Diagnostic Enable Switch. If the condition generating the diagnostic occurs only for a brief moment, the message will disappear and the diagnostic code will be Logged in the ECM memory.Logged Diagnostic Codes
When the ECM generates a diagnostic code, it usually logs the code in permanent memory within the ECM. The ECM has an internal diagnostic clock and will record the hour of the first occurrence, the hour of the last occurrence and the number of occurrences of the code. Knowing when and how often the code was generated can be a valuable indicator when troubleshooting intermittent problems.An Electronic Service Tool can retrieve and delete Logged codes. Any Logged diagnostic codes will automatically be deleted if no additional occurrences are recorded in 100 hours.When investigating logged diagnostic codes, keep in mind the following information.* Some diagnostic codes may be sensitive, and may log occurrences that did not result in operator complaints. If the time the code was logged does not correlate to a complaint, there may be nothing to repair.* The most likely cause of an intermittent problem is a faulty connection or damaged wiring. Next likely is a component failure (sensor or switch). Least likely is failure of the ECM itself.* Diagnostic codes that are logged repeatedly may indicate a problem that needs special investigation.To troubleshoot a Logged diagnostic code, refer to the Quick Reference Sheet For Diagnostic Codes in this section. The code number will direct you to a procedure in Section 5: Functional Tests. If the symptoms continue, use the proper procedure for troubleshooting the symptoms that have been experienced by the operator. Refer to Section 3: Troubleshooting Without a Diagnostic Code. Always clear logged diagnostic codes after investigating and correcting the problem which generated the code.
Figure 4.1 - Reference: Output Voltage from an Analog Temperature Sensor. The diagram shown is for reference only and should not be used to troubleshoot an Analog Temperature Sensor.Logged Events
The ECM stores a historical record of the actions taken when parameters exceed their limits. This is known as event logging and can be a useful tool when troubleshooting. Events refer to engine operating conditions such as low oil pressure or high coolant temperature. Logged events do not indicate an electronic system problem, but may indicate an engine system problem. The example diagram shown indicates the output voltage from an Analog Temperature Sensor and how the ECM responds to the signal voltage. This diagram is only an example, do not use the diagram shown to troubleshoot an Analog Temperature Sensor. Refer to P-599: Event Code Test in Section 5 for additional information.Using the ECAP to Display ACTIVE or LOGGED Diagnostic Codes
Figure 4.2 - Example ECAP Diagnostic Display Screen1. Connect an ECAP and Communication Adapter Tool to the Service Tool Connector.2. Turn the keyswitch to the ON position, engine OFF.3. Select the Display Diagnostics/Events option from the menu.4. Each diagnostic code CID and FMI are listed on the left and followed by a text description.5. The ECAP also displays the number of times the diagnostic code occurs and the engine hours at the first and last occurrence of the diagnostic code.6. The diagnostic status display is located on the far right of the display window. (a) The ACTIVE bar indicates the diagnostic is occurring.(b) No text present, as shown on the first two diagnostics, indicates that two codes are logged but are not active.Using ET to Display ACTIVE Diagnostic Codes
Figure 4.3 - Example ET Active Diagnostic Code Screen1. Connect ET and the Communication Adapter Tool to the Service Tool Connector.2. Turn the keyswitch to the ON position, engine OFF.3. Select the Display Active Diagnostics option from the Diagnostics Menu.4. Each Diagnostic Code CID and FMI are listed on the left followed by a text description.Using ET to Display LOGGED Diagnostic Codes
Figure 4.4 - Example ET Logged Diagnostic Code Screen1. Connect ET and the Communication Adapter Tool to the Service Tool Connector.2. Turn the keyswitch to the ON position, engine OFF.3. Select the Display Logged Diagnostics option from the Diagnostics Menu.4. Each Diagnostic Code CID and FMI are listed on the left followed by a text description.Using ET or ECAP to Display and Perform Sensor Calibrations
Figure 4.5 - Example Calibrate Sensors ScreenDiagnostic Terminology
Module Identifier (MID)Two or three digit code which is assigned to each module or control system. Component Identifier (CID)Two or three digit code which is assigned to each component or system.Failure Mode Identifier (FMI)Type of failure the component experienced (adopted from SAE standard practice J1587 diagnostics). Active CodeThe MID, CID and FMI can be sent through the CAT data link to the Communication Adapter Tool to the Electronic Service Tool (ET).Logged CodeThe diagnostic will be entered into the permanent memory (Diagnostic Log) when it becomes Active. The number of occurrences will be saved in the good to bad counter in the permanent memory (Diagnostic Log). First and last occurrence time (engine hours) will also be saved in the permanent memory (Diagnostic Log). This information is then available for display on the Electronic Service Tool (ET).Quick Reference Sheet For Diagnostic/Event Codes