Operation CHARM: Car repair manuals for everyone.
Home >> Chevrolet >> 2006 >> Impala V6-3.9L VIN 1 >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0108

P0108



DTC P0108

DTC DESCRIPTORS

DTC P0106
Manifold Absolute Pressure (MAP) Sensor Performance

DTC P0107
Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage

DTC P0108
Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






TYPICAL SCAN TOOL DATA






CIRCUIT/SYSTEM DESCRIPTION
The manifold absolute pressure (MAP) sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by engine speed, throttle opening, air temperature, and barometric pressure (BARO). A diaphragm within the MAP sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates this action into electrical resistance. The MAP sensor wiring includes 3 circuits. The control module supplies a regulated 5 volts to the sensor on a 5-Volt reference circuit. The control module supplies a ground on a low reference circuit. The MAP sensor provides a signal voltage to the control module, relative to the pressure changes on the MAP sensor signal circuit. The control module converts the signal voltage input to a pressure value.

Under normal operation, the highest pressure that can exist in the intake manifold is equal to the BARO. This occurs when the vehicle is operated at wide open throttle (WOT), or when the ignition is ON while the engine is OFF. Under these conditions, the control module uses the MAP sensor to determine the current BARO. The lowest manifold pressures occur when the vehicle is idling or decelerating. The MAP can range from 10 kPa when pressures are low to as much as 104 kPa when pressures are high, depending on the BARO.

The control module should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The control module should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a WOT.

Within the control module, the intake flow rationality diagnostic has the ability to determine an inaccurate input from the 3 systems it monitors. Calibrated within the diagnostic are estimates for the MAP, the mass air flow (MAF), and the throttle position (TP) for all engine operating conditions.

The diagnostic uses the following system of models and calculations that are then compared to the actual measured values from the MAF, MAP, and the TP sensors and to each other to determine the appropriate DTC to fail.
- The throttle model describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of BARO, TP, intake air temperature (IAT), and estimated MAP.
- The intake manifold model describes the intake manifold and is used to estimate the MAP as a function of the MAF into the manifold from the throttle body, and the MAF out of the manifold caused by engine pumping. The flow into the manifold from the throttle uses the MAF estimate calculated from the above throttle model.

CONDITIONS FOR RUNNING THE DTC

P0106
- DTCs P0016, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335, or P0336 are not set.
- The engine is running.
- The engine coolant is between 70-125°C (158-257°F).
- The intake air temperature is between -7 and +125°C (+19.4 and +257°F).

P0107
- DTCs P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0641, P0651 or P2135 are not set.
- The engine is running greater than or equal to 400 RPM.
- The throttle position is greater than or equal to 0 percent when the engine speed is less than or equal to 1,000 RPM. OR
- The throttle position is greater than or equal to 12.5 percent when the engine speed is greater than 1,000 RPM.

P0108
- The engine has been running for a length of time that is determined by the start-up coolant temperature. The length of time ranges from 5.5 minutes at less than -30°C (-22°F) to 10 seconds at more than +30°C (+86°F).
- DTCs P0120, P0121, P0122, P0123, P0220, P0222, P0223, or P2135 are not set.
- The engine is running.
- The throttle position is less than or equal to one percent when the engine speed is less than or equal to 1,200 RPM. OR
- The throttle position is less than or equal to 20 percent when the engine speed is greater than 1,200 RPM.

CONDITIONS FOR SETTING THE DTC

P0106
- The control module detects the MAP sensor is not within the predicted range for more than 2 seconds.
- This diagnostic runs continuously.

P0107
- The control module detects that the MAP sensor voltage is less than 0.05 volt for more than 5 seconds.
- This diagnostic runs continuously.

P0108
- The control module detects that the MAP sensor voltage is more than 4.9 volts for more than 5 seconds.
- This diagnostic runs continuously.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

CIRCUIT/SYSTEM TESTING
1. Start the engine.
2. Monitor the diagnostic trouble code (DTC) information with the scan tool.
3. If DTC P0641 or P0651 is also set, then correct DTC P0641 or P0651 first.
4. Inspect for the following conditions:
- Disconnected, damaged, or incorrectly routed vacuum hoses
- Manifold absolute pressure (MAP) sensor disconnected from the vacuum source
- Restrictions in the MAP sensor vacuum source
- Intake manifold vacuum leaks
- Check for a properly functioning oxygen sensor, refer to Scan Tool Data List. Scan Tool Data List
5. With the ignition ON, and the engine OFF.
6. Disconnect the MAP sensor.
7. Measure for 4.8-5.2 volts from the 5-Volt reference circuit of the MAP sensor to a good ground, with a DMM.
- If more than 5.2 volts, then test the 5-Volt reference circuit for a short to voltage or faulty control module.
- If less than 4.8 volts, than test the 5-Volt reference circuit for high resistance, an open, or an intermittent and poor connection or at the control module, or a faulty control module.
8. Use a scan tool and observe the MAP sensor for less than 12 kPa.
- If the MAP sensor is more than 12 kPa, then test the MAP sensor signal circuit for a short to voltage or a faulty control module.
9. Use a 3-amp fused jumper wire and connect it between the MAP sensor 5-Volt reference circuit and the MAP sensor signal circuit.
10. Observe the MAP sensor for more than 103 kPa.
- If the MAP sensor is less than 103 kPa, then test the MAP sensor signal circuit for a short to ground or high resistance or a faulty control module.
11. With the 3-amp fused jumper wire still connected between the 5-Volt reference circuit of the MAP sensor and the signal circuit of the MAP sensor, observe the MAP sensor parameter with the scan tool for 4.9V.
- If less than 4.9V, test the MAP sensor signal circuit for a short to ground, an open, or high resistance, or an intermittent and for a poor connection at the control module, if tests OK then replace the control module.
12. Turn OFF the ignition and allow the control module to power down.
13. With a DMM measure for less than 5 ohms of resistance between the low reference circuit of the MAP sensor and a good ground.
- If the resistance is more than 5 ohms, then test the circuit for an open, high resistance, or a faulty control module.
14. Turn OFF the ignition.
15. Remove the MAP sensor from the engine vacuum source. Leave the MAP sensor connected to the engine harness.
16. Connect a Mityvac to the MAP sensor.
17. Turn ON the ignition, with the engine OFF.
18. Observe the MAP sensor pressure with the scan tool.
19. Apply vacuum to the MAP sensor with the in 1 inch Hg increments until 15 inches Hg is reached. Each 1 inch Hg should decrease MAP sensor pressure by 3-4 kPa. Monitor the MAP sensor pressure to see if the decrease in pressure in consistent.
- If decrease in pressure is not consistent then, test for intermittent and poor connections at the MAP sensor. If connections test OK, replace the MAP sensor.
20. Apply vacuum with the until 20 inches Hg is reached. Observe the MAP sensor pressure for less than 34 kPa.
- If more than 34 kPa, test for an intermittent and for a poor connection at the MAP sensor. If connections test OK, replace the MAP sensor.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Manifold Absolute Pressure (MAP) Sensor Replacement
- Control Module References Verification Tests
pro multis · About Operation CHARM