G643(E) Service Manual
Chapter 5. Engine Management System (EMS)
177
A Throttle Position Sensor (TPS), (
Figure 18
) which
is integral to the Drive By Wire (DBW) throttle
assembly, provides feedback for position control by
monitoring the exact position of the throttle valve.
NOTE:
The DV-E5 is not a serviceable assembly.
If the TPS sensor fails, the assembly should be
replaced.
Figure 18. Throttle Position Sensor (TPS) on DV-
E5 Throttle
SECM self-calibration and “cross checking” of the
TPS is accomplished by comparing the TPS signal
to a calculated throttle position in the SECM
software (Predicted TPS). In addition to the throttle
position sensor, a temperature/manifold air pressure
sensor (TMAP) is used to monitor intake manifold
temperature and pressure (
Figure 19
). This enables
the SECM full control capabilities monitoring actual
airflow in relationship to desired airflow. The
TMAP
sensor is a single unit incorporating both intake
manifold temperature and manifold pressure
measurement.
Figure 19. TMAP Sensor
The MI-07 system also performs minimum (min) and
maximum (max) governing through the SECM and
DBW throttle. For min governing, or idle speed
control, the idle speed is fixed by the SECM. Unlike
a mechanical system, the idle speed is not
adjustable by the end user. The idle speed is
adjusted by the SECM based on engine coolant
temperature. At these low engine speeds, the SECM
uses spark and throttle to maintain a constant speed
regardless of load.
