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Makes 🢒 Chevrolet 🢒 2000 🢒 Malibu 🢒 Engine 🢒 Engine Controls - 3.1L (LG8) 🢒 Manifold Absolute Pressure Sensor Circuit Diagnosis

Object Number: 568087 Size: LF
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The manifold absolute pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). The MAP sensor signal voltage to the Powertrain Control Module (PCM) varies from below 2 volts at idle (high vacuum) to above 4.0 volts with the key ON and the engine OFF, or at wide-open throttle (low vacuum). The MAP sensor is used to determine manifold pressure changes while the EGR flow test diagnostic is being run, to update the barometric pressure reading (BARO), and as a enabling factor for other diagnostics. Refer to DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient . The powertrain control module (PCM) monitors the MAP signals for voltages outside the normal range of the MAP sensor. If the PCM detects a MAP signal voltage that is excessively high, refer to DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage will be set. If the PCM detects a MAP signal voltage that is excessively low DTC P0107 will be set.

Diagnostic Aids

Inspect for the following conditions:

    •  Monitor the MAP sensor using a scan tool. If the MAP sensor does not respond to throttle changes, inspect the 3X reference circuits from the ignition control module to the PCM.
         If the 3X reference signal is lost the PCM will only update the MAP sensor reading once per key cycle, when the engine is first started.
         Depending upon where the MAP sensor voltage (high voltage or low voltage) is when the engine is started, the high or low voltage MAP sensor DTCs will set.
    •  Inspect for kinked and damaged vacuum hoses. Ensure that a good vacuum source is available. Refer to Emission Hose Routing Diagram .

Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: :  Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

    • Loose terminal connection
       -  Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
       -  Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
    • Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
    •  Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Inspect for the following conditions:
    2. • A missing or damaged MAP sensor seal.
    • Disconnected, damaged, incorrectly routed vacuum hoses.
    •  Intake manifold vacuum leaks.
    •  Vacuum leaks at the throttle body.
    •  Vacuum leaks at the EGR gasket.
    • A faulty, missing, or incorrectly installed positive crankcase ventilation valve
  2. If a problem is found, repair as necessary.

Did you find and correct any of the conditions?

--

Go to Step 14

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the MAP sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Use a scan tool in order to observe the MAP sensor voltage.

Is the voltage more than the specified value?

0.0 V

Go to Step 4

Go to Step  11

4
  1. Turn OFF the ignition.
  2. Connect a 3 amp fused jumper wire between the 5 volt reference A circuit of the MAP sensor and the signal circuit of the MAP sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool in order to observe the MAP sensor voltage.

Is the voltage near the specified value?

4.95 V

Go to Step 5

Go to Step  8

5
  1. Connect a test lamp between battery positive voltage and the MAP sensor signal circuit at the MAP sensor harness connector.
  2. Observe the MAP sensor voltage on the scan tool.

Is the voltage near the specified value?

4.95 V

Go to Step 6

Go to Step  9

6
  1. Turn OFF the ignition.
  2. Inspect for faulty connections at the MAP sensor harness connector.
  3. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 7

7
  1. Test the ground circuit for high resistance, an open between the PCM and the MAP sensor or for a faulty connection at the PCM.
  2. If a problem is found, repair as necessary. Refer to the following procedures in Wiring Systems:

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

8
  1. Test the 5 volt reference A circuit for high resistance, an open between the PCM and the MAP sensor, or a faulty connection at the PCM.
  2. If a problem is found, repair as necessary. Refer to the following procedures in Wiring Systems:

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

9
  1. Turn OFF the ignition.
  2. Test the signal circuit of the MAP sensor for high resistance, an open, a short to ground, or a short to the sensor ground circuit.
  3. If a problem is found, repair as necessary. Refer to the following procedures in Wiring Systems:

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

10
  1. Test the signal circuit of the MAP sensor for a faulty connection at the PCM.
  2. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

11
  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Turn ON the ignition, with the engine OFF.
  4. Test the signal circuit of the MAP sensor for a short to voltage or a short to the 5 volt reference A circuit.
  5. If a problem is found, repair as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

--

12

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

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

13

Important::  Perform the set up procedure for the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Did you find and correct the condition?

--

Go to Step 14

--

14

With the engine idling, monitor the MAP sensor with a scan tool while increasing the engine RPM.

Does the MAP sensor value change?

--

System OK

Go to Step 2