Failure Mode

Failure Mode Identifier (FMI) Usage and Definitions Definitions, Acronyms and Abbreviations ATA: CID: DOUT: DTC: ECU: EID:

Fault Code: FMI: OBDII:

PID: SAE: SID: SPN: WCI:

American Trucking Association Component Identifier (CDL)[although this is really a circuit identifier] Digital OUTput driver in the ECU. Diagnostic Trouble Code. This is the combination of the Fault Code and the FMI. Electronic Control Unit. This has also been called ECM (Electronic Control Module) in the past. Event IDentifier. In Cat Data Link, some diagnostics are called events. Events are valid signals that are outside acceptable range (like overheating), position (coasting in neutral), or status. See Cat Data Link standards for more details. This is a term for use in this document to describe: CIDs for Cat Data Link, SPNs for SAE J1939, and SID or PID for ATA (SAE J1587). Failure Mode Identifier On-Board Diagnostics, level II. This is a legal requirement to support advanced on-board diagnostics for emissions monitoring and generic scan tool compatibility. Parameter ID - identifies the data (size, scaling, units) communicated in the message Society of Automotive Engineers Subsystem Identifier (ATA) Suspect Parameter Number (SAE J1939) Warning Category Indicator (used on Cat Data Link).

Standard Definition of an FMI The Failure Mode Identifiers (FMI’s) are used with Fault Codes to provide more information on why a circuit or subsystem is faulting. The combined Fault Code/FMI is called a Diagnostic Trouble Code or DTC.

Failure Mode Identifier (FMI) Usage Failure Mode Identifiers are used to indicate the detection method, not the estimated root cause. For instance, FMI 03 is for a diagnostic that trips due to voltage higher than expected. This condition can be caused by an array of root causes. All the ECU can detect is that the voltage on the pin is higher than the diagnostic trip point, and that is exactly the FMI we should use for this fault. When applying FMI’s, always think in terms of “what is wrong with this signal” rather than “what do we think caused it”.

Nomenclature The text descriptions for DTC should indicate the detection method and the circuit or subsystem it was detected on, not the estimated root cause or component. For instance, FMI 03 is for a diagnostic that trips due to voltage higher than expected. The description for this FMI in service tools and displays should read: [Fault Code] “voltage high” (for example “engine coolant temperature voltage high”). This is all we really know. This condition can be caused by an array of root causes. All the ECU can detect is that the voltage on the pin is higher than the diagnostic trip point, and that is exactly what we should communicate to the technician. In order to maintain consistency with EID nomenclature, some test descriptions come in front of the fault code descriptions, and others after.

1.1. FMI 00: Data Valid but above Normal Operating Range (most severe) 1.1.1.

Definition The signal communicating information is within a defined acceptable and valid range, but the real world condition is above what would be considered normal as determined by the predefined most severe level limits for that particular measure of the real world condition. Broadcast of data values is continued as normal. Every electronic control system sets a high limit for the the “expected” operating range of the signal. The limit includes “over range” signals such as high converter temperatures. For example for a sensor, an FMI 00 would be stored if the sensed value was within the measuring capabilities of the sensor, but the sensed value is above the expected limit for the application. This is not to be used for “open circuit!” This is to be used for things like overheating, overpressure, and so forth. (Region 'e' of the signal range definition).

1.1.2.

Data Link Applicability This FMI is generally not appropriate for CDL since CDL uses Event IDentifiers (EIDs) and Warning Category Indicators (WCIs) in place of this FMI. On SAE J1939, this is used to report the most severe level (equivalent to WCI level 3).

1.2. FMI 01: Data Valid But Below Normal Operating Ope rating Range (most severe) 1.2.1.

Definition The signal communicating information is within a defined acceptable and valid range, but the real world condition is below what would be considered normal as determined by the predefined least severe level limits for that particular measure of the real world condition. Broadcast of data values is continued as normal. Every electronic control system sets a low limit for the “expected” operating range of the signal. The limit includes “under range” signals such as a low engine oil pressure signal from a working sensor. For example for a sensor, an FMI 01 would be stored if the sensed value was within the measuring capabilities of the sensor, but the sensed value is below the expected limit for the application. This is not to be used for short circuit! This is used for things like low oil pressure and the sort. (Region 'd' of signal range definition).

1.2.2.

Data Link Applicability This FMI is generally not appropriate for CDL since CDL uses Event IDentifiers (EIDs) and Warning Category Indicators (WCIs) in place of this FMI. On SAE J1939, this is used to report the most severe level (equivalent to WCI level 3).

1.3. FMI 02: Data Erratic, Intermittent or Incorrect 1.3.1.

Definition Erratic or intermittent data includes all measurements that change at a rate that is not considered possible in the real world condition and must be caused by improper operation of the measuring device or its connection to the module. Signal data from a component is present, at least intermittently. The signal is either unstable or invalid as recognized by the control doing diagnostics. Data can be correct sometimes and not at other times. This is different from FMI 10. FMI 2 is used for situations where the rate of change is not physically possible. FMI 10 is used for situations where the rate of change is physically possible, but outside the predefined limits of a properly functioning system. FMI 2 is also also used for data that is invalid, such as an invalid state of a parity switch.

1.3.2.

Data Link Applicability This FMI code is acceptable for use on all data links.

1.4. FMI 03: Voltage Above Normal 1.4.1.

Definition The voltage identified is higher than expected from the component or system that the Fault Code identifies. FMI 03 relates to a signal circuit. In general, this FMI refers to the input but it can be used for any circuit that is using voltage on the ECU pin to detect faults. A voltage signal, data or otherwise, is above the predefined limits that bound the range. (Region 'g' of the signal range definition).

1.4.2.


1.5. FMI 04: Voltage Below Normal 1.5.1.

Definition Reference FMI 03 except voltage is lower than expected. In general, this FMI refers to the input circuit but it can be used for any circuit that is using voltage on the ECU pin to detect faults. A voltage signal, data or otherwise, is is below the predefined limits that bound the range. (Region 'f' of the signal range definition).

1.5.2.


1.6. FMI 05: Current Below Normal 1.6.1.

Definition The control detects that the current in the monitored circuit described by the Fault Code is less than expected and usually results from an open circuit. Generally, FMI 05 is related to a control output driver circuit. A current signal, data or otherwise, is below the predefined limits that bound the range. (Region 'f' of the signal range definition).

1.6.2.


1.7. FMI 06: Current Above Normal 1.7.1.

Definition The same as FMI 05 except current is higher than expected. For example, when a circuit is shorted to ground causing excessive current. In general, this FMI refers to the output. A current signal, data or otherwise, is above the predefined limits that bound the range. (Region 'g' of the signal range definition).

1.7.2.


1.8. FMI 07: Mechanical System Not Responding Properly 1.8.1.

Definition Any fault that is detected as the result of an improper response or action of a mechanical system. This type of fault may or may not be directly associated with the value of general broadcast information. When an electronic control sends an electrical command command or output to a mechanical system and the result is not as expected, as evidenced by some other means (sensor). This FMI should be applied to the output driver circuit and not the sensor. An example would be HEUI rail pressure control. There is an output from the ECU that controls rail pressure. There is a pressure sensor that measures the rail pressure. If the desired rail pressure is 10Mpa, and the current is sent to the pump control to develop that pressure, but the sensor reads only 2Mpa and will not rise, then FMI 07 is the proper FMI to apply. The Fault Code should be for the oil pressure control circuit and not the pressure sensor. This is not to be confused with an FMI 00 or 01 where it is just the measured signal that is out of range. In the FMI 07 case, it is the response of the system as measured by a feedback device that is incorrect.

1.8.2.

Data Link Applicability This FMI code is acceptable for use on all data links. However, this FMI is generally not appropriate for CDL since CDL uses Event IDentifiers (EIDs) and Warning Category Indicators (WCIs) in place of this FMI.

1.9. FMI 08: Abnormal Frequency, Pulse Width or Period 1.9.1.

Definition When the signal frequency, or width of a given signal pulse, is not in the expected range. This can also be related to a faulty or open sensor output circuit. To be considered in cases of FMI 4 and 5. Any frequency or PWM signal that is outside the predefined limits which bound the signal range for frequency or duty cycle (outside Region 'b' of the signal definition). Also if the signal is an ECU output, any signal whose frequency or duty cycle is not consistent with the signal which is emitted.

1.9.2.


1.10. FMI 09: Abnormal Update Rate 1.10.1. Definition Related to communication between electronic controls on a data link. FMI 09 occurs when a given control is not able to get any information from another when the data is required or expected. Any failure that is detected when receipt of data via the data link or as input from a smart actuator or smart sensor is not at the update rate expected or required by the ECU. Also any error that causes the ECU not to send information at the rate required by the system. This type of fault may or may not be directly associated with the value of general broadcast information. (outside Region 'c' of the signal range definition).

1.10.2. Data Link Applicability This FMI code is acceptable for use on all data links.

1.11. FMI 10: Abnormal Rate of Change 1.11.1. Definition Relates to signal that changes at a rate faster/slower than expected. The RATE OF CHANGE is outside of the expected maximum or minimum value. Any data, exclusive of the abnormalities covered by FMI 2, that is considered valid but whose data is changing at a rate that is outside the predefined limits that bound the rate of change for a properly functioning system. Broadcast of data values is continued as normal. (outside Region 'c' of the signal range definition). This is different from FMI 2. FMI 2 is used for situations where the rate of change is not physically possible. FMI 10 is used for situations where the rate of change is physically possible, but outside the predefined limits of a properly functioning system.


1.12. FMI 11: Failure Mode Not Identifiable 1.12.1. Definition Relates to a signal where there are unique failure modes that do not fit any other FMI. This FMI must be avoided if another FMI is appropriate. Troubleshooting documentation must clearly explain what situation(s) cause this FMI to be raised.

1.12.2. Data Link Applicability This FMI code is acceptable for use on all data links. Note: for ATA only, multilevel events are not supported with the normal FMI’s. For instance, an engine overheat could only be reported as an FMI 00. If you have a warning level (FMI 00), and also want to report a derate at another level, an FMI 11 could be used for the second (more severe) level.

1.13. FMI 12: Bad Device or Component 1.13.1. Definition Inconsistency of data indicates that a device with some internal intelligence, such as a controller, module, smart sensor or smart actuator, is not properly functioning. This data may be internal to a module or external from a data link message or from various system responses. This error is to include all internal controller trouble codes that cannot be caused

by connections or systems external to the controller. This code should be avoided since it will drive replacement of the component that the Fault Code describes.


1.14. FMI 13: Out of calibration 1.14.1. Definition A failure that can be identified to be the result of not being properly calibrated. This failure mode does not relate to the signal range definition, as do many of the FMI’s.


1.15. FMI 14: Special Instruction 1.15.1. Definition This FMI is to be used where a special procedure or more detailed information is required to understand it. In many cases, it is not really a failure that occurred but rather a situation that needs to be logged to give the the service person information. This must be supported by detailed information in the troubleshooting guide. The goal is to refer the service personnel to the manufacturer's troubleshooting manual for more information on the particular diagnostic code. This FMI does not relate to the signal range definition, as do many of the FMI’s. This type of fault may or may not be directly associated with the value of general broadcast information. Example – Rated engine power special instruction (ATA/J1939). This is a normal derate that occurs when coolant temperature exceeds 103C (a normal but somewhat high temperature). The code is logged so the service person knows why the engine lost power so he does not try to fix it.


1.16. FMI 15: Data Valid but above Normal Operating Range (least severe) 1.16.1. Definition The signal communicating information is within a defined acceptable and valid range, but the real world condition is above what would be considered normal as determined by the predefined most severe level limits for that particular measure of the real world condition. Broadcast of data values is continued as normal. Every electronic control system sets a high limit for the the “expected” operating range of the signal. The limit includes “over range” signals such as high converter temperatures. For example for a sensor, an FMI 15 would be stored if the sensed value was within the measuring capabilities of the sensor, but the sensed value is above the expected limit for the application. This is not to be used for “open circuit!” This is to be used for things like overheating, overpressure, and so forth. (Region i of the signal range definition).

1.16.2. Data Link Applicability On SAE J1939, this is used to report the least severe level (equivalent to WCI level 1).

1.17. FMI 16: Data Valid but above Normal Operating Range (moderate severity) 1.17.1. Definition The signal communicating information is within a defined acceptable and valid range, but the real world condition is above what would be considered normal as determined by the predefined most severe level limits for that particular measure of the real world condition. Broadcast of data values is continued as normal. Every electronic control system sets a high limit for the the “expected” operating range of the signal. The limit includes “over range” signals such as high converter temperatures. For example for a sensor, an FMI 16 would be stored if the sensed value was within the measuring capabilities of the sensor, but the sensed value is above the expected limit for the application. This is not to be used for “open circuit!” This is to be used for things like overheating, overpressure, and so forth. (Region k of the signal range definition).

1.17.2. Data Link Applicability On SAE J1939, this is used to report the moderate severity level (equivalent to WCI level 2).

1.18. FMI 17: Data Valid But Below Normal Operating Range (least severe) 1.18.1. Definition The signal communicating information is within a defined acceptable and valid range, but the real world condition is below what would be considered normal as determined by the predefined least severe level limits for that particular measure of the real world condition. Broadcast of data values is continued as normal. Every electronic control system sets a low limit for the “expected” operating range of the signal. The limit includes “under range” signals such as a low engine oil pressure signal from a working sensor. For example for a sensor, an FMI 17 would be stored if the sensed value was within the measuring capabilities of the sensor, but the sensed value is below the expected limit for the application. This is not to be used for short circuit! This is used for things like low oil pressure and the sort. (Region h of signal range definition).

1.18.2. Data Link Applicability On SAE J1939, this is used to report the least severe level (equivalent to WCI level 1).

1.19. FMI 18: Data Valid But Below Normal Operating Range (moderate severity) 1.19.1. Definition The signal communicating information is within a defined acceptable and valid range, but the real world condition is below what would be considered normal as determined by the predefined least severe level limits for that particular measure of the real world condition. Broadcast of data values is continued as normal. Every electronic control system sets a low limit for the “expected” operating range of the signal. The limit includes “under range” signals such as a low engine oil pressure signal from a working sensor. For example for a sensor, an FMI 01 would be stored if the sensed value was within the measuring capabilities of the sensor, but the sensed value is below the expected limit for the application. This is not to be used for short circuit! This is used for things like low oil pressure and the sort. (Region j of signal range definition).

1.19.2. Data Link Applicability On SAE J1939, this is used to report a moderate severity level (equivalent to WCI level 2).

1.20. FMI 19: Received Network Data In Error 1.20.1. Definition Any failure that is detected when the data received via the network is found substituted with the “error indicator” value (i.e. FE16, see J1939-71) or DSI for CDL. This type of failure is associated with received network data. The component used to measure the real world signal is wired directly to the module sourcing the data to the network and not to the module receiving the data via the network. This FMI is applicable to Regions f and g of the signal range definition.

1.20.2. Data Link Applicability J1939 and CDL.

1.21. FMI 20: Data Drifted High The J1939 Subcommittee has defined FMI 20 and FMI 21 as 'Data Drifted High' and 'Data Drifted Low', respectively. These new FMIs (Failure Mode Indicators) complement FMI 2 for ' Data Erratic, Intermittent or Incorrect'. The new FMIs are established to communicate the parameter information is within a defined acceptable and valid range but the real world condition is above/below what would be considered normal when compared to other measurements. This may include sensor drifts, measurements that do not seem possible when compared with other data, measurements that change at a rate that is not considered possible in the real world or whose values themselves do not seem possible in the real world. FMI 2 should be used by applications that do not distinguish the high and low data conditions separately.

1.22. FMI 21: Data Drifted Low See above

1.23. FMI 22-30: Reserved 1.24. FMI 31: Not Available Or Condition Exists 1.24.1. Definition Used to indicate that the FMI is not available or that the condition that is identified by the SPN exists. When no applicable FMI exists for the reported SPN, FMI 31 can be used. Also in cases when the reported SPN name has the failure information in it, FMI 31 can be used to indicate that the condition reported by the SPN exists. This type of fault may or may not be directly associated with the value of general broadcast information.

1.24.2. Data Link Applicability J1939 only.

Failure Mode

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