HARNESS AS-SENSOR 3764208 - Caterpillar

Diagnostic Codes
The engine's Electronic Control Module (ECM) has the ability to monitor the circuitry between the ECM and the engine's components. The ECM also has the ability to monitor the engine's operating conditions. If the ECM detects a problem, a code is generated.There are two categories of codes:
Diagnostic code
Event codeDiagnostic Code - A diagnostic code indicates an electrical problem such as a short circuit or an open circuit in the engine's wiring or in an electrical component.Event Code - An event code is generated by the detection of an abnormal engine operating condition. For example, an event code will be generated if the oil pressure is too low. In this case, the event code indicates the symptom of a problem. Event codes indicate mechanical problems rather than electrical problems.Codes can have two different states:
Active
LoggedActive Diagnostic Codes
An active code indicates that an electrical problem is present. Service the active code first. For the appropriate troubleshooting procedure for a diagnostic code, refer to Troubleshooting, "Diagnostic Trouble Code List".Logged Diagnostic Codes
The codes are logged and stored in the ECM memory. The problem may have been repaired and/or the problem may no longer exist. If the system is powered, it is possible to generate an active diagnostic code whenever a component is disconnected. If the component is reconnected, the code is no longer active but the code may become logged.Logged codes may not indicate that a repair is needed. The problem may have been temporary. Logged codes may be useful to help troubleshoot intermittent problems. Logged codes can also be used to review the performance of the engine and of the electronic system.Active Event Codes
An active event code represents a problem with engine operation. Correct the problem as soon as possible.Active event codes are listed in ascending numerical order. The code with the lowest number is listed first.Illustration 1 is an example of the operating range of a temperature sensor. Do not use the Illustration to troubleshoot temperature sensors.
Illustration 1 g01138880
Example of the typical operating range of a temperature sensor (1) This area represents the normal operating range of the parameter. The normal output voltage of the sensor is between 0.2 VDC and 4.2 VDC. (2) In this area, the temperature above 107 °C (225 °F) is higher than normal. The output voltage of the sensor will generate an event code. The sensor does not have an electronic problem. (3) In these areas, the output voltage of the sensor is too high or too low. The voltage is outside of the normal range. The electronic problem will generate a diagnostic code. Refer to Troubleshooting, "Diagnostic Trouble Code List" for additional information on diagnostic codes.Events are represented in two formats. In the first format, the "E" means that the code is an event code. The "XXX(X)" represents a numeric identifier for the event code. This is followed by a description of the code. If a warning, a derate, or a shutdown is applicable, the numeric identifiers are different. Refer to the following example:
E004(3) Engine