Manifold Absolute Pressure Sensor Circuit Diagnosis. Pontiac Grand Prix 1999

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1999 🢒 Grand Prix 🢒 Engine 🢒 Engine Controls - 3.1L 🢒 Manifold Absolute Pressure Sensor Circuit Diagnosis

To read and clear diagnostic trouble codes, use a scan tool.

Use a scan tool to clear diagnostic trouble codes from the PCM memory. Diagnostic trouble codes can also be cleared by turning OFF the ignition and disconnecting the battery power from the PCM for 30 seconds, but this method will also cause all diagnostic information in the PCM memory to be cleared and all the diagnostic tests will have to be ran again.

The Vehicle Identification Number (VIN) is programmed into the PCM. Do not exchange a PCM from another vehicle for testing or replacement. When replacing the PCM, the VIN must also be programmed into the new PCM.

Because the PCM can have a failure which may affect only one circuit, follow the diagnostic procedures in this section to determine which circuit has a problem and where it is.

If a diagnostic chart indicates that the PCM connections or PCM is the cause of a problem and the PCM is replaced, but does not correct the problem, one of the following may be the reason:

•	There is a problem with the PCM terminal connections. The diagnostic chart will say PCM connections or PCM. The terminals may have to be removed from the connector in order to check them properly. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs and Wiring Repairs .

•	EEPROM program is not correct for the application. Incorrect components may cause a malfunction and may or may not set a DTC.

•

The problem is intermittent. This means that the problem is not present at the time the system is being checked. In this case, refer to the Symptoms portion of the manual and make a careful physical inspection of all components and wiring associated with the affected system. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs and Wiring Repairs .

•	There is a shorted solenoid, relay coil, or harness. Solenoids and relays are turned ON and OFF by the PCM using internal electronic switches called drivers. A shorted solenoid, relay coil, or harness will not damage the PCM but will cause the solenoid or relay to be inoperative.

Step

Action

Value(s)

Yes

Was the Powertrain on Board Diagnostic System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Check for the following conditions:

•	MAP sensor seal missing or damaged.

•	Vacuum hoses disconnected, damaged, incorrectly routed.

•	Intake manifold vacuum leaks.

•	Vacuum leaks at throttle body.

•	Vacuum leaks at EGR valve flange and pipes.

•	Positive crankcase ventilation valve faulty, missing, or incorrectly installed.

If a problem is found, repair as necessary.

Was a problem found?

Go to Step 14

Go to Diagnostic Aids

Disconnect the MAP sensor electrical connector.
Observe the MAP value displayed on the scan tool.

Is the MAP value near the specified value?

0.0V

Go to Step 4

Go to Step 12

Connect a J 35616-200 test lamp between battery positive voltage and the MAP sensor signal circuit at the MAP sensor harness connector.
Observe the MAP value displayed on the scan tool.

Is the MAP value near the specified value?

4.95V

Go to Step 5

Go to Step 8

Jumper the 5 Volt Reference A circuit and the MAP signal circuit together at the MAP sensor harness connector.
Observe the MAP value displayed on the scan tool.

Is MAP value near the specified value?

4.95V

Go to Step 6

Go to Step 7

Turn the ignition off.
Disconnect the PCM and check the sensor ground circuit for high resistance, an open between the PCM and the MAP sensor or for a poor connection at the PCM.
If a problem is found, repair as necessary. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs .

Was a problem found?

Go to Step 14

Go to Step 10

Check the 5 Volt Reference A circuit for high resistance, an open between the PCM and the MAP sensor or a poor connection at the PCM.
If a problem is found, repair as necessary. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs .

Was a problem found?

Go to Step 14

Go to Step 9

Turn the ignition off.
Disconnect the PCM, and check the MAP sensor signal circuit for high resistance, an open, a short to ground, or a short to the sensor ground circuit.
If a problem is found, repair as necessary. Refer to Wiring Repairs .

Was a problem found?

Go to Step 14

Go to Step 9

Check the MAP sensor signal circuit for a poor connection at the PCM
If a problem is found, repair as necessary. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

Did the terminal require replacement?

Go to Step 14

Go to Step 13

Check for a poor connection at the MAP sensor.
If a problem is found, repair as necessary. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

Was a problem found?

Go to Step 14

Go to Step 11

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

Is the action complete?

Go to Step 14

Turn the ignition off.
Disconnect the PCM.
Turn the ignition on.
Check the MAP signal circuit for a short to voltage or a short to the 5 Volt Reference A circuit.
If a problem is found, repair as necessary. Refer to Wiring Repairs .

Was a problem found?

Go to Step 14

Go to Step 13

Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

Go to Step 14

With engine idling, monitor MAP Sensor with scan tool while increasing engine RPM.

Does MAP sensor value change?

System OK

Go to Step 2