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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 P0102 >> Test Description
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Test Description

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

  1. 5:  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 References: Engine Controls Connector End Views or Engine 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 and idle the engine.
  2. Observe the MAF Sensor parameter with a scan tool.
Is the MAF sensor parameter less than the specified value?		 2.0 g/s Go to Step 4  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. 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
Did you find and correct the condition?		 - Go to Step 13  Go to Step 5 
5 
  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 and Circuit 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 6  Go to Step 10 
6
    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. Disconnect the harness connector of the MAP sensor.
  2. 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.
  3. 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 8  Go to Step 7 
7 Test the MAF sensor signal circuit for the following conditions:
  • An open
  • A short to ground
  • High resistance
  • 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 13  Go to Step 9 
8 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 13  Go to Step 11 
9 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 13  Go to Step 12 
10
IMPORTANT: The engine 1 voltage circuit of the MAF sensor is spliced to other components of the vehicle.
Repair the ignition 1 voltage circuit of the MAF sensor for the following conditions:Did you complete the repair?		 - Go to Step 13  -
11 Replace the MAF sensor.
Did you complete the replacement?		 - Go to Step 13  -
12 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 13  -
13
  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 14 
14 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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