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Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 3:  This step will determine if any mechanical faults have caused this DTC to set.
  2. 6:  This voltage drop test will determine if high resistance has caused this DTC to set.
  3. 8:  This step verifies the voltage signal from the ECM to the MAF sensor connector.
  4. 9:  This step will determine if the ECM can accurately process the frequency signal that it receives from the MAF sensor.
  5. 10:  This step will determine if an abnormal resistance of less than 1,150 ohms has skewed the MAF sensor frequency signal.
DTC P0101

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Observe the Freeze Frame/Failure records for this DTC.
  2. Turn OFF the ignition for 60 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 3  Go to Diagnostic Aids
3 
  1. Turn OFF the ignition.
  2. Inspect for the following conditions:
    • A restricted or collapsed air intake duct
    • A misaligned air intake duct
    • A dirty or deteriorating air filter element
    • Any objects blocking the air inlet screen of the mass air flow (MAF)/intake air temperature (IAT) sensor
    • Any contamination or debris on the sensing elements of the MAF/IAT sensor
    • Any water intrusion in the induction system
    • Any vacuum leak downstream of the MAF/IAT sensor
    • Any type of restriction in the exhaust system-Refer to Restricted Exhaust .
    • Inspect the harness of the MAF sensor to verify that it is not routed too close to the following components:
Did you find and correct the condition?		 - Go to Step 18  Go to Step 4 
4
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 temperature may cause a reading to be slightly out of range.
  1. Accurately determine the altitude.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the MAP Sensor kPa parameter with a scan tool.
  4. The MAP sensor pressure should be within the specified range for your altitude. Refer to Altitude vs Barometric Pressure .
Is the manifold absolute pressure (MAP) sensor pressure within the specified range as indicated on the Altitude vs. Barometric pressure table?		 - Go to Step 5  Go to DTC P0106 
5
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the MAP Sensor parameter with a scan tool.
  3. Start the engine.
Did the MAP Sensor parameter decrease when the engine was started?		 - Go to Step 6  Go to DTC P0106 
6 
  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the MAF/IAT sensor.
  3. Measure the battery voltage with a DMM.
  4. Turn ON the ignition, with the engine OFF.
  5. Connect a test lamp between the 12-volt reference circuit of the MAF sensor and a good ground. Refer to Circuit Testing .
  6. Connect a DMM to the probe of the test lamp and a good ground. Refer to Measuring Voltage Drop and Circuit Testing
Is the voltage within 1.5 volts of the specified value?		 B+ Go to Step 7  Go to Step 14 
7
IMPORTANT: All electrical components and accessories must be turned OFF.
  1. Turn OFF the ignition for 60 seconds to allow the control modules to power down.
  2. Measure the resistance from the low reference circuit of the MAF sensor to a good ground with a DMM. Refer to Circuit Testing .
Is the resistance less than the specified value?		 5 Ω Go to Step 8  Go to Step 15 
8 
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the signal circuit of the MAF sensor to a good ground with a DMM. Refer to Circuit Testing .
Is the voltage within the specified range?		 4-4.4 V Go to Step 9  Go to Step 11 
9 
  1. Turn OFF the ignition.
  2. Connect the voltage supply and the ground lead of the J 38522  Variable Signal Generator to the vehicle. See Special Tools .
  3. Connect the red lead of the J 38522  to the signal circuit of the MAF sensor. See Special Tools . Refer to Probing Electrical Connectors .
  4. Set the Duty Cycle switch of the J 38522  to Normal. See Special Tools .
  5. Set the Frequency switch of the J 38522  to 5 K. See Special Tools .
  6. Set the Signal switch of the J 38522  to 5 V. See Special Tools .
  7. Start the engine and allow it to idle.
  8. Observe the MAF Sensor parameter with a scan tool.
Is the MAF Sensor parameter within the specified range?		 4,950-5,025 Hz Go to Step 10  Go to Step 11 
10 
IMPORTANT: The J 38522  is able to overcome an abnormal resistance on the signal circuit of up to 1,150 ohms. See Special Tools . The MAF sensor will not be able to overcome a resistance this high.
  1. Turn OFF the ignition.
  2. Disconnect the engine control module (ECM).
  3. Test the MAF sensor signal circuit for a high resistance. Refer to Circuit Testing .
Did you find and correct the condition?		 - Go to Step 18  Go to Step 12 
11
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the MAF sensor signal circuit for a high resistance. Refer to Circuit Testing .
Did you find and correct the condition?		 - Go to Step 18  Go to Step 13 
12 Test for an intermittent and for a poor connection at the MAF/IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections , Repairing Connector Terminals , and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 18  Go to Step 16 
13 Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections , Repairing Connector Terminals , and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 18  Go to Step 17 
14 Repair the high resistance in the MAF sensor 12-volt reference circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 18  -
15 Repair the high resistance in the MAF sensor low reference circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 18  -
16 Replace the MAF/IAT sensor. Refer to Mass Air Flow (MAF) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 18  -
17 Replace the ECM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 18  -
18
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 60 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 19 
19 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
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