GM Service Manual Online
For 1990-2009 cars only

Object Number: 191668  Size: SF
Cell 21: IAT, ECT, TP, MAP Sensors
Engine Controls Components
OBD II Symbol Description Notice
ESD Notice

Circuit Description

The Manifold Absolute Pressure sensor is a sensor that changes resistance based upon manifold vacuum. The PCM provides a 5 volt reference and ground. The MAP sensor signal varies between ground and 5 volts as manifold vacuum varies. As MAP decreases, voltage decreases, low engine load, high vacuum. As MAP increases, voltage increases, high engine load, low vacuum. The PCM uses the MAP sensor values as an indicator of engine load. A short to ground or open condition would cause the MAP sensor signal to go low, setting DTC P0107.

Conditions for Running the DTC

    •  DTCs P0122 and P0123 not set.
    •  Engine speed 700 RPM or less.
    •  TP sensor 18 degrees or less.

OR

    •  DTCs P0122 and P0123 not set.
    •  Engine speed 1800 RPM or less.
    •  TP sensor 13 degrees or greater.
    •  Transaxle not in PARK or NEUTRAL.

Conditions for Setting the DTC

The MAP sensor reading has been 0.08 volts or less.

Action Taken When the DTC Sets

    •  PCM disables long term fuel trim.
    •  PCM uses a substitute MAP value based on engine RPM and throttle angle.
    •  PCM uses 92.2 kPa for barometric pressure.
    •  PCM disables Evaporative Emission (EVAP) control solenoid.
    •  PCM disables torque management.
    •  Transaxle shift adapts are maintained at current levels.
    •  The PCM will illuminate the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
    •  The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC

    •  The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
    •  A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
    •  A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.
    • Use a scan tool to clear DTCs.
    • Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in Powertrain Control Module Description .

Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

  1. If MAP sensor or circuitry are open, the MAP sensor parameter will read 10-16 kPa.

    If fault is not present monitor the scan tool display for this sensor while manipulating the vehicle's electrical harness. A change in sensor output while manipulating the harness may indicate a circuit fault.

  2. Checking if circuitry from sensor to PCM is able to respond to a 5 volt signal on MAP input. A reading of 103-105 means wiring and PCM are OK.

  3. Disconnect the suspect sensor and re-measure the resistance between the 5 volt reference and sensor ground circuits. If infinite resistance is measured the sensor is shorted.

Step

Action

Value(s)

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. Turn the key ON.
  2. Using a scan tool view the MAP display.

Is the value displayed the same or less than the value specified?

17 kPa

Go to Step 3

Fault not present. Go to DTC P0106 diagnosis

3

  1. Turn the key to OFF.
  2. Disconnect the MAP sensor.
  3. Jumper the sensor signal and 5 volt reference circuits together.
  4. Turn the key ON.

Is the MAP value displayed on the scan tool higher than the value specified?

102 kPa

Go to Step 13

Go to Step 4

4

  1. Remove the jumper.
  2. Using DMM J 39200 measure the voltage to ground at the 5 volt reference circuit terminal.

Is the voltage the same or higher than the voltage specified?

4.5 volts

Go to Step 5

Go to Step 7

5

  1. Record the fluid life indexes, turn the key to OFF and wait 30 seconds.
  2. Disconnect PCM connector C1.
  3. Measure and record the resistance between the sensor signal and the sensor ground circuit.
  4. Measure and record the resistance between the sensor signal circuit and a known good engine ground.

Is the resistance of both checks the same or more than the value specified?

10K ohms

Go to Step 6

Go to Step 9

6

Measure the resistance of the sensor signal circuit between the PCM connector terminal and the MAP sensor connector terminal.

Is the resistance more than the value specified?

5 ohms

Go to Step 10

Go to Step 19

7

  1. Record the fluid life indexes, turn the key to OFF and wait 30 seconds.
  2. Disconnect PCM connector C1.
  3. Measure and record the resistance between the 5 volt reference circuit and the sensor ground circuit.
  4. Measure and record the resistance between the 5 volt reference circuit and a known good engine ground.

Is the resistance of both checks the same or more than the value specified?

10K ohms

Go to Step 8

Go to Step 12

8

Measure the resistance of the 5 volt reference circuit between the MAP sensor connector terminal and the PCM connector terminal.

Is the resistance less than the value specified?

5 ohms

Go to Step 15

Go to Step 11

9

Repair the short to ground in the MAP Sensor Signal circuit or the short between the MAP Sensor Signal and the MAP Sensor ground circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

10

Repair the open in the MAP Sensor Signal circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

11

Repair the open in the MAP sensor 5 Volt Reference circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

12

Repair the short to ground in the MAP Sensor 5 volt reference circuit or the short between the MAP Sensor 5 volt reference circuit and the MAP Sensor ground circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

13

  1. Check terminal contact at the MAP sensor.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 14

14

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

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

15

A short to ground may exist on another 5 volt reference circuit.

    • Reconnect all sensors.
    • Disconnect PCM connector C1.
    • Using DMM J 39200 measure and record the resistance between the 5 volt reference circuit and the sensor ground circuit for each of the following sensors:
       - the TP sensor
       - the EGR valve pintle position sensor
       - the Fuel Tank Pressure sensor

Is the resistance of any check less than the value specified?

10K ohms

Go to Step 17

Go to Step 16

16

Measure and record the resistance between the 5 volt reference circuit and a known good engine ground for each of the following sensors:

    • the TP sensor
    • the EGR valve pintle position sensor
    • the Fuel Tank Pressure sensor

Is the resistance of any check less than the value specified?

10K ohms

Go to Step 18

Go to Step 19

17

Repair the 5 volt reference circuit to sensor ground short or replace the shorted sensor for the circuit that measured low in Step 15. Refer to Test Descriptions.

Is the repair or replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

18

Repair the 5 volt reference circuit short to engine / body ground for the sensor that measured low in Step 16.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

19

  1. Check terminal contact at PCM Connector C1.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 20

20

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

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--