P0108
DTC P0108 MANIFOLD ABSOLUTE PRESSURE / BAROMETRIC PRESSURE CIRCUIT HIGH INPUTComponent Location:
GENERAL DESCRIPTION
The amount of intake air flow must be inputted to PCM in order to determine the fuel injection quantity. To measure the pressure inside of intake manifold, MAFS is used at idle and MAPS is required during acceleration. 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 output 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 4.5 V 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:
Specification:
Schematic Diagram:
Signal Waveform And Data:
SIGNAL WAVEFORM AND DATA
It is necessary that MAPS should be checked along with TPS.Because The MAPKPS 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
1. 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"?
YES - Go to "Terminal and connector inspection" procedure.
NO - 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, bending, 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.
3. Has a problem been found?
YES - Repair or replace if necessary and go to "Verification of Vehicle Repair" procedure
NO - Go to 'Power Circuit Inspection" procedure.
POWER CIRCUIT INSPECTION
- CHECK VOLTAGE
1. IG "OFF".
2. Disconnect MAPS connector.
3. IG "ON".
4. Measure the voltage between power terminal of MAPS harness connector and ground.
Specification : Approx. 5 V
5. Is the measured voltage within specification?
YES - Go to "Ground Circuit Inspection" procedure.
NO
- If the voltage is over 5.1 V, 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
1. 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")
5. Measure the voltage between power and ground terminals of MAPS harness connector. (Measurement "B")
Specification : "A" - "B" = : Approx. below 200 mV
6. Is the measured voltage within specification?
YES - Go to "Signal Circuit Inspection" procedure.
NO - Repair contact resistance or open in harness and then go to "Verification of Vehicle Repair" procedure.
SIGNAL CIRCUIT INSPECTION
- CHECK SHORT TO BATTERY IN HARNESS
1. IG "OFF"
2. Disconnect MAPS and PCM connector.
3. Measure resistance between signal and power terminals of MAPS harness connector.
Specification : Infinite
4. Is the measured resistance within specification?
YES - Go to "Component Inspection" procedure.
NO - Repair contact resistance or open in harness and then go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. 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.
Specification:
3. Start engine and monitor the signal waveforms during accelerating and decelerating
4. Is the waveform displayed correctly?(Compare the response time of TPS and MAPS)
YES - 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.
NO - 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
4. Is parameter displayed "History(Not Present) fault"?
YES - System performing to specification at this time. Clear the DTC.
NO - Go to the applicable troubleshooting procedure.