DTC P0106. Chevrolet TrailBlazer

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2005 🢒 TrailBlazer - 2WD 🢒 Accessories 🢒 Navigation Systems 🢒 DTC P0106

Circuit Description

The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), manifold absolute pressure (MAP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.

•	The throttle model describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), TP, intake air temperature (IAT), and estimated MAP.

•

The first intake manifold model describes the intake manifold and is used to estimate MAP as a function of the MAF into the manifold from the throttle body and the MAF out of the manifold caused by engine pumping. The flow into the manifold from the throttle uses the MAF estimate calculated from the above throttle model.

•	The second intake manifold model is identical to the first intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input.

•	A fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model.

The estimates of MAF and MAP obtained from this system of models and calculations are then compared to the actual measured values from the MAF, MAP, and the TP sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible failure combinations and the resulting DTC or DTCs.

Throttle Model	First Intake Manifold Model	Second Intake Manifold Model	Fourth Model	DTCs Passed	DTCs Failed
X	X	Pass	Pass	P0101 P0106 P0121 P1101	None
Pass	Pass	Failed	Pass	P0101 P0106 P0121 P1101	None
Failed	Pass	Failed	Pass	P0106 P0121 P1101	P0101
Pass	Failed	Failed	Pass	P0101 P0121 P1101	P0106
Failed	Failed	Failed	Pass	P0121 P1101	P0101 P0106
X	X	Pass	Failed	P0101 P0106 P1101	P0121
Pass	Pass	Failed	Failed	P0101 P0106 P0121 P1101	None
Failed	Pass	Failed	Failed	P0101 P0106 P0121	P1101
X	Failed	Failed	Failed	P0101 P0106 P0121	P1101

If the engine control module (ECM) detects that the actual measured airflow from MAF, MAP, and TP is not within range of the calculated airflow that is derived from the system of models, DTC P0106 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0106 Manifold Absolute Pressure (MAP) Sensor Performance

Conditions for Running the DTC

•	DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0335, P0336 are not set.

•	The engine speed is between 450-6,800 RPM.

•	The IAT Sensor parameter is between -7°C and +125°C (19-257°F).

•	The ECT Sensor parameter is between 70-125°C (158-257°F).

•	This DTC runs continuously within the enabling conditions.

Conditions for Setting the DTC

The ECM detects that the actual measured airflow from MAF, MAP, and TP is not within range of the calculated airflow that is derived from the system of models for more than 0.5 second.

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.

This step tests the ability of the MAP sensor to correctly indicate BARO.

This step tests the ability of the MAP sensor to respond to an increase in engine vacuum.

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

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

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

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

Are DTCs P0107 or P0108 set?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

Inspect for the following conditions:

•	Vacuum hoses that are disconnected, damaged, or incorrectly routed

•	Manifold absolute pressure (MAP) sensor seal that is missing or damaged

•	Restrictions in the MAP sensor vacuum source

•	Intake manifold vacuum leaks

Did you find and correct the condition?

Go to Step 22

Go to Step 4

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 5

Go to Step 6

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

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

3 kPa

Go to Step 7

Go to Step 12

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.

Turn ON the ignition, with the engine OFF.
Observe the MAP sensor pressure with a scan tool. Refer to Altitude Versus Barometric Pressure .
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 7

Go to Step 12

Turn OFF the ignition.
Remove the MAP sensor from the intake manifold. Refer to Manifold Absolute Pressure Sensor Replacement . Leave the MAP sensor connected to the electrical harness.
Connect a J 23738-A Mityvac to the MAP sensor.
Turn ON the ignition, with the engine OFF.
Observe the MAP sensor pressure with a scan tool.
Apply vacuum to the MAP sensor with the J 23738-A until 5 inches Hg is reached.

Does the MAP sensor pressure change?

Go to Step 8

Go to Step 12

Observe the MAP sensor pressure with the scan tool.
Apply vacuum to the MAP sensor with the J 23738-A in 1 inch Hg increments until 15 inches Hg is reached. Each 1 inch Hg should decrease MAP sensor pressure by 3-4 kPa.

Is the decrease in MAP sensor pressure consistent?

Go to Step 9

Go to Step 12

Observe the MAP sensor pressure with the scan tool.
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 10

Go to Step 12

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

Does the MAP sensor pressure return to the original reading observed in step 4 or step 5?

Go to Step 11

Go to Step 20

Inspect for the following conditions:

•	Incorrect cam timing--Refer to Timing Chain and Sprocket Replacement for the correct timing.

•	Restricted exhaust flow--Refer to Restricted Exhaust .

•	Worn piston rings--Refer to Engine Compression Test .

Did you find and correct the condition?

Go to Step 22

Go to Testing for Intermittent Conditions and Poor Connections

Test for an intermittent and a poor connection at the MAP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 22

Go to Step 13

Disconnect the MAP sensor harness connector.
Turn ON the ignition, with the engine OFF.
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".
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.
Measure the amperage with the DMM. Note the measurement as "Amperage".

Is the amperage equal to the specified value?

0 mA

Go to Step 17

Go to Step 14

Remove the DMM from the circuit.
Connect the test lamp between the 5-volt reference circuit and the low reference circuit of the MAP sensor, at the harness connector.
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".

Important: Before any calculations are performed, ensure that all measurement are converted to like units, such as volts/amps or millivolts/milliamps.

Subtract the "Load voltage drop" from the "Supply voltage". Note the result as "Supply voltage drop".
Divide the "Supply voltage drop" by the amperage.

Is the result more than the specified value?

5 ohms

Go to Step 16

Go to Step 15

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".
Divide the "Low reference voltage drop" by the amperage.

Is the result more than the specified value?

5 ohms

Go to Step 18

Go to Step 20

Test the 5-volt reference circuit between the engine control module (ECM) and the MAP sensor for high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 22

Go to Step 19

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

Did you find and correct the condition?

Go to Step 22

Go to Step 19

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

Did you find and correct the condition?

Go to Step 22

Go to Step 19

Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 22

Go to Step 21

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

Did you complete the replacement?

Go to Step 22

Replace the ECM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 22

Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
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 23

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK