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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1381 (Engine Control System Diagnosis (DTC P0505 To DTC P2445) -- 1.8L (LNK)) >> Diagnosis >> DTC P2431 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Vibe. 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. 1:  The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 2:  If the AIR pump is always ON, DTC P2431 can set. DTC P2444 will locate and repair the cause of a stuck ON AIR pump.
  3. 3:  This step determines if DTC P2431 is the result of a hard failure or an intermittent condition. Normal pressure sensor input voltage is approximately 1.6 volts with the ignition ON, AIR pump OFF.
  4. 5:  This step determines if there is trapped pressure at the AIR pressure sensor.
  5. 8:  This step inspects for excessive resistance in the reference voltage circuit. If the test lamp does not illuminate at all, there is resistance in the circuit.
  6. 10:  This step checks for high electrical resistance in the AIR pressure sensor input circuit.
  7. 11:  This step checks for high electrical resistance in the AIR pressure sensor ground circuit.
DTC P2431

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Powertrain Control Module (PCM) Connector End Views  or  Engine Controls 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. Turn ON the ignition, with the engine OFF.
  2. Listen for secondary AIR pump operation.
Is the secondary AIR pump ON?		 - Go to DTC P2444  Go to Step 3 
3 
  1. Turn ON the ignition, with the engine OFF.
  2. Backprobe the input circuit of the secondary AIR pressure sensor with a DMM to ground.
Is the pressure sensor input circuit voltage within the specified value?		 1.5-1.6 V Go to Step 4  Go to Step 5 
4
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the input circuit voltage of the AIR pressure sensor while operating the AIR pump.
  3. Command the AIR solenoid and pump ON with the scan tool. Refer to Scan Tool Output Controls .
Did the pressure sensor voltage increase to at least the specified value when the AIR pump was ON?		 1.9-2.1 V Go to Diagnostic Aids Go to Step 7 
5  Disconnect the pressure sensor hose.
Is the pressure sensor input circuit voltage within the specified value?		 1.5-1.6 V Go to Step 6  Go to Step 7 
6 Repair the cause of the trapped air pressure in the AIR system.
Did you complete the repair?		 - Go to Step 15  -
7
  1. Inspect the following conditions:
    • A disconnected or restricted vacuum hose to the AIR pressure sensor
    • A loose or restricted air hose from the AIR pump to the AIR shut-off valve
  2. Repair as necessary.
Did you find and correct a condition?		 - Go to Step 15  Go to Step 8 
8 
  1. Connect a test lamp to the reference voltage circuit and ground.
  2. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate at least dimly?		 - Go to Step 9  Go to Step 13 
9 Measure the voltage of the AIR pressure sensor input circuit on the harness side using a DMM.
Is the voltage near the specified value?		 4.9 V Go to Step 11  Go to Step 10 
10 
  1. Test the input circuit of the AIR pressure sensor for high resistance. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Was a repair necessary?		 - Go to Step 13  Go to Step 14 
11 
  1. Test for high resistance in the ground circuit of the AIR pressure sensor between the sensor and the splice in the sensor ground circuit. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. Test for a poor electrical connection at the pressure sensor.
  3. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct a condition?		 - Go to Step 15  Go to Step 12 
12 Replace the AIR pressure sensor. Refer to Secondary AIR Injection Pressure Sensor Replacement .
Did you complete the replacement?		 - Go to Step 15  -
13 Repair the high resistance in the reference voltage circuit of the AIR pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Did you complete the repair?		 - Go to Step 15  -
14 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 15  -
15
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.
Did a DTC P2431 set?		 - Go to Step 2  Go to Step 16 
16 With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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