FAILURE MODE IDENTIFIERS (FMIS)
Table 1. Detailed FMI Explanation.
Data Valid but Above
Every electronic control system sets a high limit for expected signal operating
range. High limit includes over range signals. This could be a high
Range (may need
temperature. A sensor that is still operating but sending a signal above
expected limit will cause an FMI 00 to be stored. Some possible causes of an
FMI 00 diagnostic code are: Signal is above normal.
Signal is above normal.
Signal is shoted to + batt.
Sensor needs to be calibrated so that a PWM signal at a duty cycle of 80
percent is a valid signal. If PWM signal has a duty cycle of 81 percent,
sensor is still working, but sensor signal is above expected signal limits.
Every electronic control system sets a low limit for expected signal operating
Data Valid but Below
range. Low limit includes signals under lower limit. Low signal could be oil
pressure signal. Sensor is still working, but sending a signal below expected
Range (may need
limit will cause an FMI 01 to be stored. Some possible causes of an FMI 01
diagnostic code are:
Timing is retarded.
Signal is below normal range so thata PWM sensor is not expected to
generate a PWM signal below a duty cycle of 5 percent with zero air pres-
sure. If sensor generates a signal with a duty cycle of 4 percent when
engine is shut down, sensor is still working but sending a signal below
expected limit, which will cause an FMI 01 to be stored.
A signal from a component is present. Control that reads diagnostic
information can not read signal properly. Signal appears to be gone, unstable,
or invalid. Data can be correct or incorrect intermittently. Also, this condition
relates to communication between controls. For example, when monitoring
system is looking for engine speed from engine ECM over CAT data link.
Some possible causes of an FMI 02 diagnostic code are:
There is a faulty connection.
Signal is intermittent or erratic.
Software has been changed.
Signal is noisy.
Signal is out of range.