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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1865 (Engine Controls And Fuel - 3.5L (L66) - DTC P0506 To DTC P2199) >> DTC P1129 >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 1:  The Diagnostic System Check - Vehicle 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. 4:  This step checks for a faulty vacuum supply to the MAP sensor. The scan tool will indicate higher than normal MAP sensor voltage, if the manifold vacuum signal does not reach the MAP sensor vacuum port.
  3. 10:  After replacing the PCM, a new minimum throttle position and idle speed must also be established.
DTC P1129

Step Action Value(s) Yes No
Connector End View Reference: Powertrain Control Module 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
  1. Start the engine.
  2. Install a scan tool.
  3. Select the MAP sensor parameter on the scan tool.
Is the manifold absolute pressure (MAP) sensor voltage equal to or more than the specified value?		 2.7 V Go to Step 4  Go to Step 3 
3
  1. Turn ON the ignition, with the engine OFF.
  2. Perform the scan tool Clear DTC Information function.
  3. Operate the vehicle within the Freeze Frame conditions as noted.
  4. Observe the MAP sensor voltage on the scan tool.
Did a DTC P1129 set or was the MAP sensor voltage always more than the specified value?		 2.7 V Go to Step 4  Go to Diagnostic Aids
4 
  1. Turn OFF the ignition.
  2. Inspect for the following conditions:
    • A vacuum leak at the MAP sensor
    • A plugged MAP sensor vacuum port
    • A blockage in the intake manifold vacuum passage to the MAP sensor
  3. Repair as necessary.
Did you find and correct the condition?		 - Go to Step 11  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Disconnect the MAP sensor electrical connector.
  3. Connect a test lamp to the harness side of the MAP sensor ground circuit and B+.
  4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate?		 - Go to Step 6  Go to Step 7 
6
  1. Connect a DMM to the harness side of the MAP sensor signal circuit and ground.
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the DC voltage with the DMM.
Is the voltage near the specified value?		 0 V Go to Step 9  Go to Step 8 
7 Repair the open circuit or poor connection in the MAP sensor ground circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 11  -
8
  1. Check for a short to voltage in the MAP sensor signal circuit.
  2. Repair as necessary. Refer to Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 11  Go to Step 10 
9 Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement .
Did you complete the replacement?		 - Go to Step 11  -
10 
  1. Replace the powertrain control module (PCM). Refer to Control Module References for replacement, setup, and programming.
  2. Perform the idle learn procedure. Refer to Idle Learn .
Did you complete the replacement?		 - Go to Step 11  -
11
  1. Use the scan tool in order to clear the DTCs.
  2. Turn the ignition OFF for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC or until the DTC P1129 diagnostic has passed.
Does the DTC run and pass?		 - Go to Step 12  Go to Step 2 
12 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 - Vehicle System OK
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