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Home >> Cadillac >> 2005 >> XLR >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls (DTC P0010 To P0153) >> DTC P0102 >> Test Description

Test Description

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

  1. 4:  This step will determine if a shorted component has caused this DTC to set.
  2. 5:  This step will determine if a shorted component has caused this DTC to set.
  3. 6:  This step will determine if any mechanical faults have caused this DTC to set.
  4. 7:  This voltage drop test will determine if high resistance has caused this DTC to set.
  5. 9:  This step verifies the voltage signal from the ECM to the MAF sensor connector.
  6. 11:  This step will determine if the ECM can accurately process the frequency signal that it receives from the MAF sensor.
  7. 12:  This step will determine if an abnormal resistance of less than 1,150 ohms has skewed the MAF sensor frequency signal.
DTC P0102

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 in Vehicle DTC Information
2
IMPORTANT: A short to ground on the 12-volt reference circuit of the mass air flow (MAF) sensor that is spliced to other components of the vehicle will result in a no start condition.
Attempt to start the engine.Does the engine start?		 - Go to Step 3  Go to Step 4 
3
  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 6  Go to Diagnostic Aids
4 
  1. Disconnect the MAF/intake air temperature (IAT) sensor.
  2. Attempt to start the engine.
Does the engine start?		 - Go to Step 21  Go to Step 5 
5 
  1. Turn ON the ignition, with the engine OFF.
  2. Connect a test lamp between the 12-volt reference circuit of the MAF sensor and a good ground. Refer to Probing Electrical Connectors and Circuit Testing in Wiring Systems.
  3. Observe the test lamp.
  4. Disconnect the remaining sensors one at a time that share the 12-volt reference circuit of the MAF/IAT sensor.
Did the test lamp illuminate when any of the sensors were disconnected?		 - Go to Step 19  Go to Step 15 
6 
  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/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 in Engine Exhaust.
  3. Inspect the harness of the MAF/IAT sensor to verify that it is not routed too close to any of the following components:
Did you find and correct the condition?		 - Go to Step 27  Go to Step 7 
7 
  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 Probing Electrical Connectors and Circuit Testing in Wiring Systems.
  6. Connect a 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 1.5 volts of the specified value?		 B+ Go to Step 8  Go to Step 17 
8
IMPORTANT: All electrical components and accessories must be turned OFF.
  1. Remove the test lamp.
  2. Turn OFF the ignition for 60 seconds to allow the control modules to power down.
  3. Measure the resistance from the low reference circuit of the MAF sensor to a good ground with a DMM. Refer to Probing Electrical Connectors and Circuit Testing in Wiring Systems.
Is the resistance less than the specified value?		 5 Ω Go to Step 9  Go to Step 18 
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 Probing Electrical Connectors and Circuit Testing in Wiring Systems.
Is the voltage within the specified range?		 4-4.4 V Go to Step 11  Go to Step 10 
10 Is the voltage more than the specified value? 4.4 V Go to Step 14  Go to Step 13 
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. 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 in Wiring Systems.
  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 12  Go to Step 13 
12 
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 in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 20 
13
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the MAF sensor signal circuit for the following conditions:
    • A high resistance
    • An open circuit
    • A short to ground

      Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?		 - Go to Step 27  Go to Step 22 
14
IMPORTANT: Disconnecting the ECM connectors may eliminate the short to voltage if the signal circuit is shorted to another ECM circuit.
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the MAF sensor signal circuit for the following conditions:
    • A short to voltage
    • A short to the IAT signal circuit
    • A short to any 5-volt reference circuit

      Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?		 - Go to Step 27  Go to Step 23 
15
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the 12-volt reference circuit of the MAF sensor for the following conditions:
Did you find and correct the condition?		 - Go to Step 27  Go to Step 16 
16 Test the 12-volt reference circuit of the following components for a short to ground:
  • The crankshaft position (CKP) sensor
  • The camshaft position (CMP) sensor bank 1 intake
  • The CMP sensor bank 1 exhaust
  • The CMP sensor bank 2 intake
  • The CMP sensor bank 2 exhaust

    Refer to Testing for Short to Ground and Circuit Testing in Wiring Systems.


Did you find and correct the condition?		 - Go to Step 27  Go to Step 23 
17 Test the MAF sensor 12-volt reference circuit for the following conditions:
  • A high resistance
  • An open circuit

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 22 
18 Test the MAF sensor low reference circuit for the following conditions:
  • A high resistance
  • An open circuit

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 22 
19 Test for shorted terminals and poor connections at the affected component. Refer to Testing for Intermittent Conditions and Poor Connections ,Repairing Connector Terminals , and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 24 
20 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 in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 25 
21 Test for shorted terminals and poor connections at the MAF/IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections ,Repairing Connector Terminals , and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 25 
22 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 in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 26 
23 Test for shorted terminals and poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections , Repairing Connector Terminals , and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 27  Go to Step 26 
24
  1. Replace the shorted component.
  2. Refer to the following appropriate removal and replacement procedure for that sensor:
Did you complete the replacement?		 - Go to Step 27  -
25 Replace the MAF/IAT sensor. Refer to Mass Air Flow (MAF) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 27  -
26 Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 27  -
27
  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 28 
28 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 in Vehicle DTC Information System OK
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