GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2004 🢒 Isuzu - N Series 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC P0106

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.

The PCM calculates a predicted value for the MAP sensor based on the throttle position (TP) and the engine speed. The PCM then compares the predicted value to the actual MAP sensor signal. If the PCM detects that the MAP sensor signal is not within the predicted range, DTC P0106 sets.

Conditions for Running the DTC
    • DTCs P0068, P0101, P0102, P0103, P0107, P0108, P0120, P0220, P0442, P0443, P0446, P0455, P1125, P1516, P2101, P2108, P2120, P2121, P2125, P2135 are not set.
    • The engine is running.
    • The engine speed is between 400-5,000 RPM.
    • Any change in the engine speed is less than 125 RPM.
    • The traction control, if equipped, is not active.
    • The power take-off (PTO), if equipped, is not active.
    • The A/C compressor clutch state does not change.
    • The clutch switch state does not change, if equipped with a manual transmission.
    • The power steering load is stable.
    • The brake switch state does not change.
    • The above conditions are met for 1 second.

Conditions for Setting the DTC

The PCM detects that the actual MAP sensor signal is not within the predicted range for 2 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 numbers below refer to the step numbers on the diagnostic table.

  1. This step tests the MAP sensors ability to correctly indicate barometric pressure.

    2.

  2. This step tests the MAP sensors ability to respond to an increase in engine vacuum.

    3.

  3. This step tests for a proper MAP sensor pressure with an applied vacuum.

    4.

  4. This step calculates the resistance in the 5-volt reference circuit.

    5.

  5. This step calculates the resistance in the low reference circuit.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Inspect for the following conditions:

    • A disconnected, damaged, or incorrectly routed vacuum hose
    • A missing or damaged manifold absolute pressure (MAP) sensor seal
    • Any restrictions in the MAP sensor vacuum source
    • Any vacuum leaks in the intake manifold

Did you find and correct the condition?

--

Go to Step 21

Go to Step 3

3

Important: The vehicle used for the comparison is not limited to the same type of vehicle as is being serviced. A vehicle known to provide an accurate reading is acceptable.

Do you have access to another vehicle in which the MAP sensor pressure can be observed with a scan tool?

--

Go to Step 4

Go to Step 5

4

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the MAP sensor pressure with the scan tool.
  3. Observe the MAP sensor pressure in the known good vehicle with the scan tool.
  4. Compare the values.

Is the difference between the values less than the specified value?

3 kPa

Go to Step 6

Go to Step  11

5

Important: The Altitude vs. Barometric Pressure table indicates a pressure range for a given altitude under normal weather conditions. Weather conditions consisting of very low or very high pressure and/or very low or very high temperature may cause a reading to be slightly out of range.

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the MAP sensor pressure with the scan tool. Refer to Altitude Versus Barometric Pressure .
  3. The MAP sensor pressure should be within the range specified for your altitude.

Does the MAP sensor indicate the correct barometric pressure?

--

Go to Step 6

Go to Step  11

6

  1. Observe the MAP sensor pressure with the scan tool.
  2. Start the engine.

Does the MAP sensor pressure change?

--

Go to Step 7

Go to Step  11

7
  1. Turn OFF the ignition.
  2. Remove the MAP sensor from the intake manifold. Leave the MAP sensor connected to the electrical harness.
  3. Connect a J 23738-A Mityvac to the MAP sensor port.
  4. Turn ON the ignition, with the engine OFF.
  5. Observe the MAP sensor pressure with the scan tool.
  6. Apply vacuum to the MAP sensor with the J 23738-A in 1 inch Hg increments until 15 inch Hg is reached. Each 1 inch Hg should decrease the MAP sensor pressure by 3-4 kPa.

Is the decrease in MAP sensor pressure consistent?

--

Go to Step 8

Go to Step  11

8

  1. Observe the MAP sensor pressure with the scan tool.
  2. Apply vacuum with the J 23738-A until 20 inches Hg is reached.

Is the MAP sensor pressure less than the specified value?

34 kPa

Go to Step 9

Go to Step  11

9
  1. Observe the MAP sensor pressure with the scan tool.
  2. Disconnect the J 23738-A from the MAP sensor.

Does the MAP sensor pressure return to the original reading observed in Step 5 or Step 6?

--

Go to Step 10

Go to Step  11

10

Inspect for the following engine conditions:

    • Incorrect cam timing.
    • A restricted exhaust flow.
    • Any worn piston rings-Refer to Engine Compression Test in Engine Mechanical.

Did you find and correct the condition?

--

Go to Step 21

Go to Intermittent Conditions

11

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 21

Go to Step 12

12
  1. Disconnect the MAP sensor harness connector.
  2. Measure the voltage from the 5-volt reference circuit of the MAP sensor to a good ground with a DMM. Note the measurement as "Supply voltage".
  3. Connect a test lamp and a DMM in series between the 5-volt reference circuit and the low reference circuit of the MAP sensor at the harness connector.
  4. Measure the amperage with the DMM. Note the measurement as "Amperage".

Is the amperage at the specified value?

0 mA

Go to Step 16

Go to Step 13

13

  1. Remove the DMM from the circuit.
  2. Connect the test lamp between the 5-volt reference circuit and the low reference circuit of the MAP sensor, at the harness connector.
  3. Measure the voltage from the 5-volt reference circuit at the test lamp to a good ground, with the DMM. Note the measurement as "Load voltage drop".
  4. Subtract the "Load voltage drop" from the "Supply voltage". Note the result as "Supply voltage drop".
  5. Divide the "Supply voltage drop" by the "Amperage".

Is the result more than the specified value?

5 ohms

Go to Step 15

Go to Step 14

14

  1. Measure the voltage from the low reference circuit of the MAP sensor at the test lamp to a good ground, with the DMM. Note the result as "Low reference voltage drop".
  2. Divide the "Low reference voltage drop" by the "Amperage".

Is the result more than the specified value?

5 ohms

Go to Step 17

Go to Step 19

15

Test the 5-volt reference circuit between the PCM and the MAP sensor for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 18

16

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

Did you find and correct the condition?

--

Go to Step 21

Go to Step 18

17

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

Did you find and correct the condition?

--

Go to Step 21

Go to Step 18

18

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 21

Go to Step 18

19

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

Did you complete the replacement?

--

Go to Step 21

--

20

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 21

--

21
  1. Clear the DTCs with the scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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 2

Go to Step 22

22

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