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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (Engine Control System - 3.8L (DTC P1125 To DTC P2A01)) >> Diagnosis >> DTC P2440 (L26, Nu3) >> Test Description

Test Description

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 4:  This step tests for a short to battery positive voltage on the AIR control solenoid valve supply voltage circuit.
DTC P2440 (L26, NU3)

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 - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Are DTCs P0412, P0418, P2430, P2431, P2432, or P2433 present? - Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Step 3 
3
  1. Start and idle the engine.
    2. IMPORTANT: The AIR diagnostic may command either or both the AIR pump relay and AIR valve relay ON when the engine is started. Allow the engine to operate approximately 2 minutes before commanding the AIR relays with the scan tool.
  2. Monitor the AIR Pressure Sensor parameter.
    3. IMPORTANT: When the AIR pump relay is commanded ON with the scan tool, only the AIR pump relay is energized. When the AIR valve relay is commanded ON with the scan tool, both the AIR pump and the AIR valve relays are energized.
  3. Command the AIR pump relay ON with the scan tool.
  4. Command the AIR vale relay ON with the scan tool.
  5. Subtract the maximum value measured with the AIR valve relay ON from the maximum value with the AIR pump relay ON.
Is the difference at least the specified amount?		 5 kPa Go to Diagnostic Aids Go to Step 4 
4 
  1. Turn OFF the ignition.
  2. Disconnect the AIR control solenoid valve/pressure sensor assembly electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the AIR solenoid supply voltage circuit harness terminal with a test lamp connected to a good ground.
Is the test lamp OFF?		 - Go to Step 5  Go to Step 6 
5
  1. Turn OFF the ignition.
  2. Connect a J 35616-D GM Approved Terminal Test Kit to the AIR pressure sensor signal circuit and the other end of the jumper wire to the 5-volt reference circuit at the AIR control solenoid valve/pressure sensor assembly harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Monitor the AIR Pressure Sensor parameter with a scan tool.
Is the voltage at least the specified value?		 4.9 V Go to Step 11  Go to Step 7 
6
  1. Turn OFF the ignition.
  2. Remove the AIR valve relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) .
  3. Turn ON the ignition, with the engine OFF.
Is the test lamp OFF?		 - Go to Step 12  Go to Step 10 
7 Test the AIR pressure sensor signal circuit for an open or high resistance.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 8 
8 Test the AIR pressure sensor 5-volt reference circuit for an open or high resistance.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 9 
9 Test for shorted connections at the powertrain control module (PCM).
Did you find and correct the condition?		 - Go to Step 14  Go to Step 13 
10 Test the AIR control solenoid valve supply voltage circuit for a short to voltage.
Did you find and correct the condition?		 - Go to Step 14  -
11 Replace the AIR control solenoid valve/pressure sensor assembly.
Did you complete the replacement?		 - Go to Step 14  -
12 Replace the AIR valve relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) .
Did you complete the replacement?		 - Go to Step 14  -
13 Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 14  -
14
  1. Ensure all components and connectors are installed and secured.
  2. Replace fuses, as necessary.
  3. Start and idle the engine.
    4. IMPORTANT: The AIR diagnostic may command either or both the AIR pump relay and AIR valve relay ON when the engine is started. Allow the engine to operate approximately 2 minutes before commanding the AIR relays with the scan tool.
  4. Observe the AIR pressure sensor parameter with a scan tool.
    5. IMPORTANT: When the AIR pump relay is commanded ON with the scan tool, only the AIR pump relay is energized. When the AIR valve relay is commanded ON with the scan tool, both the AIR pump and the AIR valve relays are energized.
  5. Command the AIR pump relay ON with a scan tool.
Does the pressure increase by at least the specified value when the AIR pump is ON?		 5 kPa Go to Step 15  Go to Step 2 
15
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start and idle 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 16 
16 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 System OK
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