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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Controls - 6.6L (LB7) 🢒 DTC P0106

Circuit Description

The barometric pressure (BARO) sensor responds to changes in altitude and atmospheric conditions. This gives the engine control module (ECM) an indication of barometric pressure. The ECM uses this information to calculate fuel delivery. The BARO sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The ECM supplies 5 volts to the BARO sensor on a 5-volt reference circuit, and provides a ground on a low reference circuit. The BARO sensor provides a voltage signal to the ECM on a signal circuit relative to the pressure changes. The ECM compares the BARO sensor to the boost sensor in order to monitor the BARO sensor operation. This DTC will set if the difference between the two sensors is more than a predetermined amount.

Conditions for Running the DTC
    • DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0236, P0237, P0238, P0335, P0336, P0500, P2228, P2229 is not set.
    • The engine speed is between 500-900 RPM.
    • The engine run time is more than 20 seconds.
    • The accelerator pedal angle is less than 20 percent.
    • The vehicle speed is less than 40 km/h (25 mph).
    • The mass air flow (MAF) is less than 50 g/s.
    • The engine coolant temperature (ECT) is more than 80°C (176°F).
    • The power take off (PTO) is OFF.
    • The above conditions exist for 5 seconds.

Conditions for Setting the DTC

The difference between the BARO sensor and the boost sensor is more than 20 kPa for 2 seconds.

Action Taken When the DTC Sets
    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC
    • 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 non-emission related diagnostic.
    • Clear 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 ability of the BARO sensor to correctly indicate barometric pressure. The value shown for the BARO sensor varies with altitude.

    2.

  2. This step tests for a sensor that is stuck in range.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls 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
  1. Turn OFF the ignition.
  2. Inspect the BARO sensor for a plugged port.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 3

3

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

Do you have access to another vehicle in which the BARO parameter can be observed with a scan tool?

5 kPa

Go to Step 4

Go to Step 5

4

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the BARO sensor pressure with a scan tool.
  3. Turn ON the ignition of the known good vehicle, leaving the engine OFF.
  4. Observe the BARO parameter of the known good vehicle with a scan tool.
  5. Compare the values.

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

5 kPa

Go to Step 6

Go to Step 9

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 BARO sensor pressure with a scan tool. Refer to Altitude Versus Barometric Pressure .
  3. The BARO sensor pressure should be within the range specified for your altitude.

Does the BARO sensor indicate the correct barometric pressure?

--

Go to Step 6

Go to Step 9

6
  1. Connect a J 23738-A Mityvac vacuum pump to the BARO sensor port.
  2. Monitor the BARO sensor pressure with the scan tool.
  3. Apply vacuum SLOWLY 1 inch Hg at a time. Each inch of vacuum should result in a 3-4 kPa drop in the BARO sensor pressure.
  4. Increase the vacuum to 20 inches Hg.

Does the scan tool indicate that the BARO sensor pressure decreases smoothly through the test?

--

Go to Step 7

Go to Step 9

7

Disconnect the hand vacuum pump from the BARO sensor port.

Does the BARO sensor pressure return to the original value that was observed in Step 4 or 5?

--

Go to Step 8

Go to Step 21

8
  1. Observe the boost sensor pressure and the BARO sensor pressure with the scan tool.
  2. Compare the values.

Is the boost sensor pressure less than the BARO sensor pressure by more than the specified value?

10 kPa

Go to DTC P0236

Go to Intermittent Conditions

9
  1. Turn OFF the ignition.
  2. Disconnect the BARO sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.

Does the scan tool indicate that the BARO sensor pressure is more than the specified value?

44 kPa

Go to Step 18

Go to Step 10

10
  1. Connect a test lamp to a good ground.
  2. Probe the 5-volt reference circuit of the BARO sensor with the test lamp.

Is the test lamp OFF?

--

Go to Step 17

Go to Step 11

11

Measure the voltage from the 5-volt reference circuit of the BARO sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure more than the specified value?

5.2 V

Go to Step 14

Go to Step 12

12

Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the BARO sensor and the signal circuit of the BARO sensor.

Does the scan tool indicate the BARO sensor pressure is more than the specified value?

200 kPa

Go to Step 13

Go to Step 16

13
  1. Turn OFF the ignition.
  2. Remove the jumper wire.
  3. Connect a jumper wire between each of the terminals in the BARO sensor harness connector and the corresponding terminal at the BARO sensor. Refer to Using Connector Test Adapters in Wiring Systems.
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage from the low reference circuit of the BARO sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.

Is the voltage more than the specified value?

0.2 V

Go to Step 15

Go to Step 19

14

Test the 5-volt reference circuit of the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 22

15

Test the low reference circuit of the BARO sensor for high resistance or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 20

16

Test the signal circuit of the BARO sensor for the following conditions:

    • A short to ground
    • An open
    • High resistance

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 20

17

Test the 5-volt reference circuit of the BARO sensor for the following conditions:

  1. A short to ground
  2. An open
  3. High resistance

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 20

18

Test the signal circuit of the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 23

Go to Step 22

19

Inspect the BARO sensor for poor connections. 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 23

Go to Step 21

20

Inspect the ECM for poor connections. 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 23

Go to Step 22

21

Replace the BARO sensor. Refer to Barometric Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 23

--

22

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 23

--

23
  1. Clear the DTCs with a 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 24

24

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