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. 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 piezoelectric 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 4.5 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:
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
1. Check DTC Status
1. Connect scantool to Data Link Connector (DLC).
2. IG "ON".
3. Select "Diagnostic Trouble Codes (DTCs)" mode, and then Press F4 (DTAL) 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, 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 terminals. 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 as necessary and go to "Verification of Vehicle Repair" procedure
NO - Go to "Power Circuit Inspection" procedure.
POWER CIRCUIT INSPECTION
1. IG "OFF"
2. Disconnect MAPS connector
3. IG "ON"
4. Measure the voltage between terminal 2 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
1. IG "OFF".
2. Disconnect MAPS connector.
3. IG "ON" & ENG "OFF"
4. Measure the voltage between terminal 2 of MAPS harness connector and chassis ground
5. Measure the voltage between terminal 2 and 4 of MAPS harness connector.
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
1. IG "OFF"
2. Disconnect MAPS and PCM connector.
3. Measure resistance between terminal 1 and 2 of MAPS harness connector.
Specification : Infinite
4. Is the measured resistance within specification?
YES - Go to "Component Inspection" procedure.
NO - Repair short to battery in harness and then go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
Specification:
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.Turn engine "ON" and monitor the waveforms accelerating or decelerating
3. ENG "ON" and monitor signal waveform during acceleration and deceleration.
4. Is the waveform displayed correctly? (Compare the response time of TPS and MAPS)
YES - Go to "Check PCM"
NO - After replacing MAPS with new one, if it operates normally, replace MAPS and go to "Verification of Vehicle Repair".
2. Check PCM
1. IG "OFF" disconnect MAPS connector
2. Connect Scantool and IG "ON" & ENG "OFF"
3. Select simulation function on scantool.
4. Simulate voltage at terminal 1 of MAPS harness connector.
5. Does the output voltage response to the change of signal by simulation?
YES - Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace if necessary and go to "Verification of Vehicle Repair" procedure
NO - Substitute with a known - goad PCM and check for proper operation. If the problem IS corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM.Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code (DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all readiness test have been verified as "Complete"
5. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.