Neon L4-2.0L DOHC (1996)
Manifold Pressure/Vacuum Sensor: Description and Operation
Related Trouble Codes & Set Conditions
MAP Sensor Voltage Too High
NAME OF CODE:
MAP Sensor Voltage Too High
WHEN MONITORED:
With engine RPM above 400 but less than 1500 and the Throttle Position (TP) sensor voltage less than 1.0 volt.
SET CONDITION:
The manifold Absolute Pressure (MAP) sensor signal voltage is greater than 4.6 volts at start or with the engine running for 1.76 seconds.
THEORY OF OPERATION:
This sensor measures manifold absolute pressure and ambient barometric pressure within the manifold. It provides a 0 to 5-volt signal to
Powertrain Control Module (PCM) cavity 36. The MAP sensor puts out a low voltage signal (0.5 to 1.8 volts) at idle when the manifold vacuum is
high, and a higher voltage signal (3.9 to 4.8 volts) at deep throttle when the manifold vacuum is low. The MAP receives a 5-volt supply from PCM
cavity 61; voltage may vary from 4.8 to 5.1 volts. The sensor ground is provided by PCM cavity 43.
POSSIBLE CAUSES:
-
Open 5-volt supply circuit
-
Sensor open internally
-
Sensor ground circuit
-
Sensor signal circuit shorted to voltage
-
Failed PCM
-
Connector terminals
-
Connector wires
MAP Sensor Voltage Too Low
Name of Code:
MAP Sensor Voltage Too Low
When Monitored:
With engine rpm above 400 but less than 1,500 and the TP sensor voltage less than 1.0 volt.
Set Condition:
The MAP sensor signal voltage is below 1.2 volts at start, or below 0.02 volt for 1.76 seconds with engine running.
Theory of Operation:
This sensor measures manifold absolute pressure and ambient barometric pressure within the manifold. It provides a 0 to 5-volt signal to PCM
cavity 36. The MAP sensor puts out a low voltage signal (0.5 to 1.8 volts) at idle when the manifold vacuum is high, and a higher voltage signal
(3.9 to 4.8 volts) at deep throttle when the manifold vacuum is low. The MAP receives a 5-volt supply from PCM cavity 61; voltage may vary
from 4.8 to 5.1 volts. The sensor ground is provided by PCM cavity 43.
Possible Causes:
-
Open 5-volt supply circuit
-
Signal circuit shorted to ground
-
Failed sensor
-
PCM failure
-
Connector terminals
-
Connector wires
No Change In MAP From Start to Run
NAME OF CODE:
No Change in MAP From Start to Run
WHEN MONITORED:
With engine RPM above 400 but less than 1500 and the throttle body at closed throttle.
SET CONDITION:
Too small a difference is seen between barometric pressure at ignition on and manifold vacuum (engine running) for 1.76 seconds.
THEORY OF OPERATION:
This sensor measures manifold absolute pressure and ambient barometric pressure within the manifold. It provides a 0 to 5-volt signal to