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Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 5:  This step will determine if any mechanical faults have caused this DTC to set.
  2. 7:  This voltage drop test will determine if high resistance has caused this DTC to set.
  3. 9:  This step verifies the voltage signal from the PCM to the MAF sensor connector.
  4. 10:  This step tests the signal circuit of the MAF sensor for a short to another 5-volt reference circuit.
  5. 11:  This step will determine if the PCM is able to process the frequency signal that it receives from the MAF sensor.
  6. 14:  This step will determine which portion of the circuit or which component is shorted to ground.
  7. 17:  This step verifies that the signal circuit is not shorted to any other PCM circuit.
DTC P0102

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Controls Connector End Views  or  Powertrain Control Module (PCM) 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 MAF Sensor parameter with a scan tool.
Is the MAF Sensor parameter less than the specified value?		 1,200 Hz 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. Observe the MAF Sensor parameter with a scan tool.
  2. Move the harness and the connector of the mass air flow (MAF)/intake air temperature (IAT) sensor.
Does the movement of the harness or the connector affect the MAF Sensor parameter?		 - Go to Step 20  Go to Step 5 
5 
  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 MAF sensor
    • Any contamination or debris on the sensing elements of the MAF sensor
Did you find and correct the condition?		 - Go to Step 28  Go to Step 6 
6 Inspect the fuse in the ignition 1 voltage circuit of the MAF sensor.
Is the fuse open?		 - Go to Step 14  Go to Step 7 
7 
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the battery voltage with a DMM.
  3. Disconnect the MAF/IAT 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 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.
Is the voltage within 0.5 volts of the specified value?		 B+ Go to Step 8  Go to Step 21 
8
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 ground circuit of the MAF sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance less than the specified value?		 5 ohm Go to Step 9  Go to Step 22 
9 
  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 in Wiring Systems.
Is the voltage within the specified range?		 4.8-5.2 V Go to Step 10  Go to Step 13 
10 
  1. Connect a 3-amp fused jumper wire between the signal circuit of the MAF sensor and a good ground. Refer to Circuit Testing in Wiring Systems.
  2. Start the engine.
  3. Observe the DTC Information with a scan tool.
Do any additional DTCs set?		 - Go to Step 24  Go to Step 11 
11 
  1. Turn OFF the ignition.
  2. Connect the voltage supply and the ground lead of the J 38522  Variable Signal Generator to the vehicle.
  3. Connect the red lead of the J 38522  to the signal circuit of the MAF sensor. Refer to Probing Electrical Connectors in Wiring Systems.
  4. Set the Duty Cycle switch of the J 38522  to Normal.
  5. Set the Frequency switch of the J 38522  to 5 K.
  6. Set the Signal switch of the J 38522  to 5 V.
  7. Start the engine.
  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 12  Go to Step 15 
12
    IMPORTANT: An abnormal resistance on the signal circuit will disable the MAF sensor frequency before the voltage starts to drop out of the correct parameter of 4.8-5.2 volts.
  1. Turn OFF the ignition.
  2. Disconnect the powertrain control module (PCM).
  3. Test the MAF sensor signal circuit for a high resistance and for a short to the IAT signal circuit.
Did you find and correct the condition?		 - Go to Step 28  Go to Step 18 
13 Is the voltage less than the specified value? 4.8 V Go to Step 15  Go to Step 16 
14 
IMPORTANT: The ignition 1 voltage circuit of the MAF sensor is spliced to other components of the vehicle.
Test the ignition 1 voltage circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 28  -
15
  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Test the signal circuit between the PCM and the MAF sensor for the following conditions:
    • A high resistance
    • An open circuit
    • A short to ground
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 28  Go to Step 17 
16
IMPORTANT: Disconnecting the PCM connectors may eliminate the short to voltage if the signal circuit is shorted to another PCM circuit.
  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the signal circuit of the MAF sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage more than the specified value?		 0 V Go to Step 23  Go to Step 17 
17  Measure the resistance from the signal circuit of the MAF sensor to all other circuits at both PCM connectors with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance less than the specified value?		 infinity ohm Go to Step 25  Go to Step 19 
18 Test for an intermittent and for a poor connection at the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections andConnector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 28  Go to Step 26 
19 Test for an intermittent and for a poor connection at the PCM. 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 28  Go to Step 27 
20 Repair the wiring or the connector as needed. Refer to Wiring Repairs and Connector Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
21 Repair the high resistance or the open in the MAF sensor ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
22 Repair the high resistance or the open in the MAF sensor ground circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
23 Repair the short to voltage in the MAF sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
24 Repair the short between the MAF sensor signal circuit and the 5-volt reference circuit for which the DTC set. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
25 Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
26 Replace the MAF/IAT sensor. Refer to Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 28  -
27 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 28  -
28
  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 29 
29 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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