Diagnose
Status September 2003 (EvoBus-Service / AFT)
Page: 66 of 83
4.1.22
Throttle-valve target position
The throttle-valve target position is a function variable calculated by the EGM in dependence on the target
torque specification and the engine speed, and is transferred to the throttle valve actuator as the target
specification in the form of a PWM signal (
Æ
see Throttle valve control).
4.1.23
Throttle-valve actual position
The throttle-valve actual position is carried out in the 1 ms time slice. The calculated throttle-valve actual
position is smoothed with a low-pass filter. The characteristic curve of the throttle-valve position sensor is
stored in the engine control unit. If the voltage of the throttle-valve position sensor is above 4.70 V or
below 0.30 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped
below" is detected and the fault code 8115 or 8116 is entered. This is only an indicator – the EGM does
not take any actions based on these events.
4.1.24
Lambda target value
The lambda target value is a function variable calculated by the EGM in dependence on the target torque
specification and the engine speed.
4.1.25
Lambda actual value
The gas lambda actual value is calculated every 10 ms. The calculated lambda actual value is smoothed
with a low-pass filter. The characteristic curve of the lambda probe is stored in the control unit software.
If the voltage of the lambda signal is above 4.90 V or below 0.15 V for more than 2 seconds, then the
event "Fault measuring range exceeded or dropped below" is detected and the fault code 0915 or 0916 is
entered. A substitute value of one is used as the lambda actual value. If the fault debouncing time has not
yet expired, however the voltage value is outside the limits, the last lambda actual value calculated under
valid conditions is retained.
4.1.26
Lambda-probe heating current
The lambda-probe heating current is calculated every 10 ms and is based on an internal voltage
measurement in the control unit. The measured voltage permits conclusions to be drawn on the probe
current and can NOT be checked outside the control unit. The characteristic conversion curve is stored in
the control unit software. The calculated lambda-probe heating current is smoothed with a low-pass filter.
The "Lambda-probe heating current" calculated by the MR EGM can be checked by connecting the
current tester to the probe heater in series.
The "Lambda-probe heating current" is continuously monitored by the EGM.
•
The MR EGM detects the event "Measuring range exceeded" (fault code 8415) when high currents
(significantly higher than 3 A) are observed by the MR. Possible causes can be a defect in the probe
heating or a short-circuit to earth in the wiring. The MR EGM detects the event "Measuring range
dropped below" (fault code 8416) when a defect in the probe heating or a break in the wiring is
present.
•
The MR EGM detects the event "Measuring range dropped below" (fault code 8416) when a defect in
the probe heating or a break in the wiring is present. The MR EGM detects the event "Measuring
range dropped below" (fault code 8416) when a defect in the probe heating or a break in the wiring is
present.