DTC P0108. Chevrolet Monte Carlo 2003

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2003 🢒 Monte Carlo 🢒 DTC 🢒 DTC P0108

Circuit Description

The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:

•	5-volt reference circuit

•	Low reference circuit

•	MAP sensor signal circuit

The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.

If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets.

Conditions for Running the DTC

•	DTCs P0121, P0122, P0123 are not set.

•	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 2 minutes at less than -30°C (-22°F) to 1 second at more than 30°C (86°F).

•	The throttle angle is less than 2 percent when engine speed is less than 1,500 RPM.

•	The throttle angle is less than 10 percent when the engine speed is more than 1,500 RPM.

Conditions for Setting the DTC

The PCM detects that the MAP sensor signal voltage is more than 4.2 volts for 7 seconds.

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.

Test Description

The number below refers to the step number on the diagnostic table.

This step tests for improper throttle position (TP) sensor operation.

If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data can aid in locating an intermittent condition.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views

Did you perform the Diagnostic System Check - Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Turn ON the ignition, with the engine OFF.
Observe the TP sensor parameter with a scan tool.
Depress the accelerator pedal slowly until the throttle is in the wide-open position.
Release the accelerator pedal slowly until the throttle is returned to the closed position.
Repeat this procedure several times.

Does the TP sensor parameter increase steadily to more than the first specified value, and then decrease steadily returning to less than the second specified value?

98%

Go to Step 3

Go to DTC P0121

Start the engine.
Observe the MAP sensor parameter with the scan tool.

Is the voltage more than the specified value?

4.2 V

Go to Step 5

Go to Step 4

Observe the Freeze Frame/Failure Records for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 5

Go to Intermittent Conditions

Inspect the MAP sensor vacuum source for the following conditions:

•

Leaks

•	Restrictions

•	Faulty Connections

Did you find and correct the condition?

Go to Step 16

Go to Step 6

Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.

Is DTC P1635 also set?

Go to Step 9

Go to Step 7

Turn OFF the ignition.
Disconnect the MAP sensor electrical connector.
Turn ON the ignition, with the engine OFF.
Observe the MAP sensor parameter with the scan tool.

Is the voltage less than the specified value?

0.1 V

Go to Step 8

Go to Step 10

Turn OFF the ignition.
Connect a jumper wire between each of the terminals in the MAP sensor harness connector and the corresponding terminal at the MAP sensor. Refer to Using Connector Test Adapters in Wiring Systems.
Turn ON the ignition, with the engine OFF.
Measure the voltage from the low reference circuit of the MAP sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.

Is the voltage more than the specified value?

0.2 V

Go to Step 11

Go to Step 12

Turn OFF the ignition.
Disconnect the MAP sensor electrical connector.
Turn ON the ignition, with the engine OFF.
Observe the MAP sensor parameter with the scan tool.

Is the voltage less than the specified value?

0.1 V

Go to DTC P1635

Go to Step 10

Important: Disconnecting the PCM may eliminate the short during testing.

Important: The MAP sensor may have been damaged if the circuit was shorted to a voltage source.

Test the MAP sensor signal circuit between the PCM and the MAP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 15

Test the low reference circuit between the PCM and the MAP sensor for high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 13

Test for an intermittent and for a poor connection at the MAP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 14

Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 15

Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement .

Did you complete the replacement?

Go to Step 16

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 16

Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed form the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 17

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK