Manifold Absolute Pressure Sensor Circuit Diagnosis. Pontiac Grand Prix 2000

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2000 🢒 Grand Prix 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Manifold Absolute Pressure Sensor Circuit Diagnosis

Engine Data Sensors-MAF, EVAP Vent, EVAP Purge, EGR
Handling ESD Sensitive Parts Notice
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure or vacuum. The MAP sensor signal voltage to the powertrain control module (PCM) varies from less than 2 volts at idle, or high vacuum, to more than 4 volts with the key ON, and with the engine not running or at wide-open throttle, or low vacuum. The MAP sensor determines the manifold pressure changes while the EGR flow test diagnostic is being run. Refer to DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient . The MAP sensor also helps to update the barometric pressure reading (BARO), and as an enabling factor for other diagnostics. The 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, 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 Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage will be set.

Diagnostic Aids

Inspect for the following conditions:

•	Use a scan tool in order to monitor the MAP sensor. If the MAP sensor does not respond to throttle changes, test 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 on the state of the MAP sensor voltage is when the engine is started, the high or low voltage MAP sensor DTCs will set.

•	Inspect the connection at the PCM. Inspect the harness connectors for the following conditions:

•	Backed-out terminals

•	Improper mating

•	Broken locks

•	Improperly-formed terminals

•	Damaged terminals

•	Poor terminal-to-wire connections

•	Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

•

A damaged harness--Inspect the wiring harness for damage. If the harness appears OK, observe the MAP display on a scan tool while moving the connectors and the wiring harnesses that are related to the sensor. A change in the display will indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.

•	Inspect for kinked and damaged vacuum hoses, and ensure that a good vacuum source is available. Refer to Emission Hose Routing Diagram .

Step

Action

Value(s)

Yes

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

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Inspect for the following conditions:

•	MAP sensor seal that is missing or damaged

•	Vacuum hoses that are disconnected, damaged, incorrectly routed

•	Intake manifold vacuum leaks

•	Vacuum leaks at the throttle body

•	Vacuum leaks at the EGR gasket

•	A positive crankcase ventilation valve that is faulty, missing, or incorrectly installed

If you find a problem, repair the condition as necessary.

Did you find and correct any of the conditions?

Go to Step 14

Go to Step 3

Turn OFF the ignition.
Disconnect the MAP sensor.
Turn ON the ignition, with the engine OFF.
With a scan tool, observe the MAP sensor voltage parameter.

Does the scan tool indicate that the MAP sensor reading is more than the specified value?

0.0 V

Go to Step 4

Go to Step 11

Turn OFF the ignition.
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.
Turn ON the ignition, with the engine OFF.
Use a scan tool in order to observe the MAP sensor parameter.

Does the scan tool indicate that the MAP sensor reading is more than the specified value?

4.95 V

Go to Step 5

Go to Step 8

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

Does the scan tool indicate that the MAP sensor voltage parameter is near the specified value?

4.95 V

Go to Step 6

Go to Step 8

Turn OFF the ignition.
Inspect for poor connections at the harness connector of the MAP sensor.
If you find a problem, repair the condition 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

Test the ground circuit for high resistance, for an open between the PCM and the MAP sensor, or for a poor connection at the PCM.
If you find a problem, repair the condition as necessary. Refer to Measuring Voltage Drop , refer to Wiring Repairs , and 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 12

Test the 5-volt reference A circuit for high resistance, for an open between the PCM and the MAP sensor, or a poor connection at the PCM.
If you find a problem, repair the condition as necessary. Refer to Measuring Voltage Drop , refer to Wiring Repairs , and 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 10

Turn OFF the ignition.
Test the signal circuit of the MAP sensor for the following conditions:

•	High resistance

•	An open circuit

•	A short to ground

•	A short to the sensor ground circuit

If you find a problem, repair the condition as necessary. Refer to Measuring Voltage Drop , refer to Wiring Repairs , and 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 10

Test the signal circuit of the MAP sensor for a poor connection at the PCM.
If you find a problem, repair the condition 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

Turn OFF the ignition.
Disconnect the PCM.
Turn ON the ignition, with the engine OFF.
Test the signal circuit of the MAP sensor for a short to voltage or a short to the 5-volt reference A circuit.
If you find a problem, repair the condition as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

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

Did you complete the replacement?

Go to Step 14

Go to Step 13

Important:: The replacement PCM must be programmed.

Refer to Powertrain Control Module Replacement/Programming .

Did you complete the replacement?

Go to Step 14

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

Does the MAP sensor value change?

System OK

Go to Step 2