Service manual

G420F(FE) Service Manual Chapter 5. Engine Management System (EMS) 193
MAP (Manifold Absolute Pressure)
Sensor
The manifold absolute pressure (MAP) sensor is a
pressure sensitive variable resistor. It measures
changes in the intake manifold pressure which result
from engine load and speed changes, and converts
this to a voltage output. The MAP sensor is also
used to measure barometric pressure at start up,
and under certain conditions, allows the ECM to
automatically adjust for different altitudes. The ECM
supplies 5 volts to the MAP sensor and monitors the
ECM supplies 5 volts to the MAP sensor and
monitors the voltage on a signal line. The sensor
provides a path to voltage on a signal line. The
sensor provides a path to ground through its
variable resistor. The MAP sensor in put affects fuel
delivery and ignition timing controls in the ECM.
Ciruit Diagram
MAP & IAT
sensor
3214
Sensor
power
B24
IAT
signal
B12
Sensor
ground
B1
MAP
signal
B18
E C M
IAT
MAP
Sensor Inspection
1. Measure the voltage between terminals 1 and 4 of
the MAP sensor connectors.
Terminal 4 : MAP sensor ground
Terminal 1 : MAP sensor output
Engine state Test specification
Ignition SW. ON 4~5V
At idle 0.5~2.0V
2. If the voltage deviates from the standard value,
replace the MAP sensor assembly.