Fuel System > Engine Control System > P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input

Component Location

General Description

The amount of intake air flow must be inputted to PCM in order to determine the fuel injection quantity. MAPS(Manifold Absolute Pressure) calculates the amount of air indirectly as measuring the pressure inside of intake manifold. This mechanism is also called Speed-Density Type.

MAPS transfers analog output signal which is proportional to the change of intake manifold pressure, then, with this signal and RPM, PCM calculates the amount of intake air flow.

MAPS is mounted on surge tank to measure the pressure inside of intake manifold, and it consists of a piezo electric element and hybrid IC which amplifies output signal from the element. A piezo electric element is a sort of a diaphragm using piezo electric effect. One side of the diaphragm is surrounded with vacuum chamber while intake pressure is applied to the other side. Thus, signals are outputted by the transformation of diaphragm according to the change of pressure inside of intake manifold.

DTC Description

Checking output signals of MAPS every 5 sec. under detecting condition, if an output signal is above 4.5V for more than 2.5 sec., PCM sets P0108. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition

Item

Detecting Condition

Possible cause

DTC Strategy

•	This code detects a continuous short to high in either the signal circuit or the MAP sensor

•	Connecting condition

•	Short to battery in Signal Circuit

•	Open in Ground Circuit

•	Faulty MAPS

•	Faulty PCM

Enable
Conditions

Case 1

•	No TPS Active Fault Present

•	Engine Running Time >10sec.

•	Engine Speed ≤ 2500rpm

•	Throttle Position ≤ 30%

Case 2

•	No TPS Active Fault Present

•	Engine Running Time >10sec.

•	Engine Speed >2500rpm

•	Throttle Position ≤ 40%

Threshold value

•	MAP Signal >4.5V

Diagnosis Time

•	Continuous (More than 2.5 seconds failure for every 5 seconds test )

MIL On Condition

•	2 Driving Cycle

Specification

Pressure(kPa)	20	35	60	95	101.32
Voltage(V)	0.789	1.382	2.369	3.75	4
Tolerance(V)	± 0.045

Schematic Diagram

Signal Waveform And Data

It is necessary that MAPS should be checked along with TPS. Because The MAP/TPS Rationality Diagnostic is comprised of two tests. A deceleration test is performed to provide a robust method for detection of an altitude compensated MAP value that is too high for the deceleration condition. The second test compares the altitude compensated MAP value to both high and low limits, dependent upon throttle position and engine speed. When the MAP value is out of the threshold range, the MAP/TPS system is determined to be failed.

Monitor DTC Status

Check DTC Status

(1)	Connect scantool to Data Link Connector(DLC).

(2)

IG "ON".

(3)	Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.

(4)	Read "DTC Status" parameter.

(5)

Is parameter displayed "Present fault"?

▶ Go to "Terminal and connector inspection" procedure.

▶ Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

Terminal And Connector Inspection

1.	Many malfunctions in the electrical system are caused by poor harness and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found ?

	▶ Repair or replace if necessary and go to "Verification of Vehicle Repair" procedure
	▶ Go to "Power Circuit Inspection" procedure.

Power Circuit Inspection

■ Check Voltage

IG "OFF".

2.	Disconnect MAPS connector.

IG "ON".

Measure the voltage between power terminal of MAPS harness connector and ground.

Specification : Approx. 5V

Is the measured voltage within specification ?

	▶ Go to "Ground Circuit Inspection" procedure.
	▶ If the voltage is over 5.1V, check short to battery in harness. ▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.

Ground Circuit Inspection

■ Check Open In Harness

IG "OFF".

2.	Disconnect MAPS connector.

3.	IG "ON" & ENG "OFF"

4.	Measure the voltage between power terminal of MAPS harness connector and chassis ground. (Measurement "A")

Measure the voltage between power and ground terminals of MAPS harness connector. (Measurement "B")

Specification : "A" - "B" = : Approx. below 200mV

Is the measured voltage within specification ?

	▶ Go to "Signal Circuit Inspection" procedure.
	▶ Repair contact reistance or open in harness and then go to "Verification of Vehicle Repair" procedure.

Signal Circuit Inspection

■ Check Short To Battery In Harness

IG "OFF"

2.	Disconnect MAPS and PCM connector.

Measure resistance between signal and power terminals of MAPS harness connector.

Specification : Infinite

Is the measured resistance within specification ?

	▶ Go to "Component Inspection" procedure.
	▶ Repair contact resistance or open in harness and then go to "Verification of Vehicle Repair" procedure.

Component Inspection

MAPS performance test

(1)

IG "OFF"

(2)	Connect scantool to Data Link Connector(DLC) and select "Oscilloscope" then, connect probes to output signal lines of MAPS and TPS.

(3)

Start engine and monitor the signal waveforms during accelerating and decelerating

Specificaton :

Pressure(kPa)	Voltage(V)	Tolerance(V)
20	0.789	± 0.045
35	1.382
60	2.369
95	101.32
3.75	4

(4)

Is the waveform displayed correctly?(Compare the response time of TPS and MAPS)

	▶ Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
	▶ After replacing MAPS with new one, if it operates normally, replace MAPS and go to "Verification of Vehicle Repair".

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.

1.	Connect scantool and select "DTC" button.

2.	Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions

3.	Read "DTC Status" parameter

Is parameter displayed "History(Not Present) fault"?

	▶ System performing to specification at this time. Clear the DTC
	▶ Go to the applicable troubleshooting procedure.