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Home >> Chevrolet >> 2005 >> Epica LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 2.5L (LBK) - DTC P0030 To DTC P0154 >> DTC P0101 >> Test Description
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Test Description

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

  1. 9:  Any un-metered air entering the engine may cause this DTC to set. This step eliminates any conditions which can cause a DTC to set with a normally operating MAF sensor.
  2. 10:  This step tests for high resistance in the ignition 1 voltage circuit of the MAF sensor. The voltage measure at the probe of the test lamp should be within a specified voltage of the battery voltage.
Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics Connector End View Reference:  Engine Controls Connector End Views  orEngine Control Module (ECM) 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. Start the engine.
  2. Observe the Diagnostic Trouble Code (DTC) Information with a scan tool.
Did the scan tool display any other DTCs set?		 - Go to Diagnostic Trouble Code (DTC) List Go to Step 3 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  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 4  Go to Diagnostic Aids
4
  1. Idle the engine.
  2. Observe the MAP sensor kPa parameter with a scan tool.
Is the MAP sensor kPa parameter less than the specified value?		 27 kPa Go to DTC P0107  Go to Step 5 
5 Does the scan tool indicate that the MAP sensor kPa parameter is more than the specified value? 103 kPa Go to DTC P0108  Go to Step 6 
6
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the MAP sensor kPa parameter with a scan tool.
  3. Compare the MAP sensor kPa parameter to a known good vehicle.
Is the MAP sensor kPa parameter within the specified value of the known good vehicle?		 3.0 kPa Go to Step 7  Go to DTC P0106 
7
  1. Observe the MAP sensor voltage parameter with a scan tool.
  2. Start the engine.
Did the MAP sensor voltage parameter change value after you started the engine?		 - Go to Step 8  Go to DTC P0106 
8
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the TP sensor voltage parameter with a scan tool.
  3. Press the accelerator pedal from a closed throttle position, to a wide open throttle position.
Did the TP sensor voltage parameter go from above the specified value to below the specified value?		 Above 4.0 V to below 1.0 V Go to Step 9  Go to DTC P0121 
9 
  1. Turn OFF the ignition.
  2. Inspect for air leaks in the following components:
    • The air induction system.
    • The MAF sensor O-ring seal
  3. Inspect for the following conditions:
    • An obstructed intake air duct or a dirty restricted air filter element
    • Any debris that is blocking the air sensing filaments of the MAF sensor
    • Contamination on the air sensing filaments of the MAF sensor
    • Water intrusion in the air induction system
    • A restricted exhaust system-Refer to Restricted Exhaust in Engine Exhaust
    • An engine vacuum leak
Did you find and correct the condition?		 - Go to Step 19  Go to Step 10 
10 
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the battery voltage with a DMM.
  3. Disconnect the harness connector of the MAF sensor.
  4. Connect a test lamp between the ignition 1 voltage circuit of the MAF sensor and a good ground. Refer to Probing Electrical Connectors andCircuit Testing in Wiring Systems.
  5. Connect the DMM to the probe of the test lamp and a good ground. Refer to Measuring Voltage Drop and Circuit Testing in Wiring Systems.
  6. Compare the battery voltage to the ignition 1 voltage of the MAF sensor.
Is the voltage within 0.5 volts of the specified value?		 B+ Go to Step 11  Go to Step 17 
11
    IMPORTANT: This procedure is using the 5 volt reference circuit of the MAP sensor to test the signal circuit of the MAF sensor. If DTC P0107 is set, refer to DTC P0107 , before proceeding with this test.
  1. Connect a 3-amp fused jumper wire between the 5 volt reference circuit of the MAP sensor and the signal circuit of the MAF sensor. Refer to Circuit Testing in Wiring Systems.
  2. Observe the MAF Sensor parameter with a scan tool.
Is the MAF Sensor parameter more than the specified value?		 4.98 V Go to Step 13  Go to Step 12 
12 Test the MAF sensor signal circuit for the following conditions:
  • High resistance
  • A short to ground
  • A short to the MAF sensor low reference circuit

    Refer to Circuit Testing and Wiring Repairs in Wiring Systems.


Did you find and correct the condition?		 - Go to Step 19  Go to Step 16 
13 Probe the low reference circuit of the MAF sensor with a test lamp connected to B+.
Does the test lamp illuminate?		 - Go to Step 15  Go to Step 14 
14 Test the low reference circuit of the MAF sensor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 19  Go to Step 16 
15 Test for shorted terminals and for an intermittent and for a poor connection at the MAF 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 20  Go to Step 18 
16 Test for shorted terminals and for an intermittent and for a poor connection at the ECM. 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 20  Go to Step 19 
17 Repair the high resistance in the ignition voltage circuit of the MAF sensor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 20  -
18 Replace the MAF sensor.
Did you complete the replacement?		 - Go to Step 20  -
19 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 20 
20
  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 21 
21 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
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