Usage:
All Machines With Electronic Controls Or Electronic Monitors Which Use Built In Diagnostics
Reference: Electrical System Schematic for the particular machine. Service Manual module for the particular electronic control system.
Description
Service codes contain three levels of information which describe one problem. The levels of the service code are MID, CID, FMI. These codes most often describe an electrical fault or failure in the ELECTRICAL system. These codes are not to be confused with an abnormal condition in the ENGINE or machine SYSTEM such as high engine coolant temperature.
The service codes that apply to a given machine are listed on the back of the electrical system schematic which is in the service manual for the machine being serviced.
MID - The MID (Module Identifier) tells which electronic control system has detected the problem. The MID is shown in the format of MIDnnnn. Where nnnn is a number describing the electronic control system. Such as: electronic engine control (36), electronic transmission control (81) or computerized monitoring system (26). The MID number can be any length from n to nnnn.
CID - The CID (Component Identifier) tells which component (or circuit) in the MID system has the problem. This code can point to items like an engine speed sensor (190), transmission oil temperature sensor (177) or 8 Volt sensor power supply (263).
FMI - The FMI (Failure Mode Identifier) tells what is believed to be wrong with the component that the CID is describing. Such as: grounded, open or shorted. The FMI is the code which is most often misunderstood. An expanded generic description of each FMI code is given in the paragraphs that follow.
FMI 00 - Data Valid But Above Normal Operating Range. Every electronic control system sets a high limit for the "expected" operating range of a signal. The limit includes over ranges like high converter temperatures. A sensor that is still working but sending a signal above the expected limit will cause the FMI 00 code to be stored.
Example - A certain pulse-width modulated (PWM) sensor is not expected to generate a valid signal over 80 percent duty cycle. If a sensor generates an 81 percent duty cycle, it is still working but is now above the expected signal limits.
FMI 01 - Data Valid But Below Normal Operating Range. Every electronic control system sets a low limit for the "expected" operating range of a signal. The limit includes under ranges like low engine oil pressure. A sensor that is still working but sending a signal below the expected limit will cause the FMI 01 code to be stored.
Example - Most pulse-width modulated (PWM) sensors are not expected to generate a valid signal less than 5 percent duty cycle. If a sensor generates a 3 percent duty cycle, it is still working but is now less than the expected signal limits.
FMI 02 - Data Erratic, Intermittent Or Incorrect. Signal data from a component is present. Then the signal is either gone, unstable or invalid as recognized by the electronic control doing diagnostics. Data can be correct sometimes and not at other times. This code also relates to communication between electronic controls. Such as when VIMS is looking for engine speed from the electronic engine control over the CAT data link.
FMI 03 - Voltage Above Normal or Shorted High.The voltage identified is HIGHER than expected from the component or system (like sensor power) that the CID identifies. FMI 03 is most often related to a signal circuit.
The responsible elements of the system can be:
The sensor.
The harness.
A related electronic control.
The possible causes of FMI 03 can be:
A sensor that does not generate an alternating signal (duty cycle) and the output stops "high" or at maximum signal output.
A harness with the sensor signal wire shorted to the sensor power supply or shorted to any voltage greater than the sensor power supply voltage.
An open sensor signal wire between the sensor and the electronic control. Electronic controls normally "pull" the input circuit to a positive voltage level. For example, 5.0 DCV when the sensor is disconnected.
A faulty electronic control where the connector contact of the sensor signal is internally shorted to a positive source. Also, a faulty electronic control (very unlikely) that believes a fault exists when the signal circuit is actually working correctly.
FMI 04 - Voltage Below Normal or Shorted Low. Reference FMI 03 except voltage is LOWER than expected. FMI 04 is most often related to a signal circuit. Very similar to FMI 06 and sometimes used instead of FMI 06.
The responsible elements of the system can be:
The sensor.
The harness.
A related electronic control.
The possible causes of FMI 04 can be:
Sensor signal stops "low" or near ground.
Harness signal wire is shorted to ground.
Electronic control has internal short to ground on connector contact of signal input.
FMI 05 - Current Below Normal or Open Circuit. The electronic control detects that the current in the monitored circuit described by the CID is less than expected. FMI 05 is most often related to a control output circuit.
The most likely cause of an FMI 05 code are open circuits or poor harness connections.
FMI 06 - Current Above Normal Or Grounded Circuit. Same as FMI 05 except current is higher than expected. FMI 06 is most often related to a control output circuit. For example, when a circuit is shorted to ground. Very similar to FMI 04 and sometimes used instead of FMI 04.
FMI 07 - Mechanical System Not Responding Properly. When an electronic control sends an electrical command or output to a mechanical system and the result is not as expected.
Example - Slow shifting of ICM transmission (EPTCII) caused by a sluggish solenoid valve.
FMI 08 - Abnormal Frequency, Pulse Width Or Period. When the signal frequency, or width of a given signal pulse, is not in the expected range. Note: Period is the time in seconds for one cycle at a given frequency or repetition rate. Period is defined as 1/frequency in Hz.
FMI 09 - Abnormal Update. Relates to communication between electronic controls on a data link. FMI 09 is stored when a given electronic control is not able to get information from another when the data is required or expected.
FMI 10 - Abnormal Rate Of Change. Relates to a signal that changes at a rate faster/slower than expected. The rate of change, not the maximum or minimum value, is outside of the expected limits.
Example - When the signal from a transmission output speed sensor (ground speed) on an OHT indicates the truck is accelerating (or decelerating) faster than could possibly occur during actual operation.
FMI 11 - Failure Mode Not Identifiable. Relates to a signal where the electronic control identifies more than one FMI as responsible for a single problem.
FMI 12 - Bad Device Or Component. Describes a condition where an electronic control sends a signal to another electronic module over a data link and expects a response but gets no response or the response is incorrect. Also applies to a condition where an electronic module is expected to send data periodically and does not. Could also relate to a faulty data link.
FMI 13 - Out Of Calibration. For a given mechanical condition, the electrical signal is not within the limits the electronic control expects.