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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1045 (Engine Controls Diagnosis - 6.6L (Lb7) (DTCS P2142 To P2279)) >> Diagnosis >> DTC P2227 (Federal RPO FE9, NG1) >> Test Description

Test Description

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

  1. 4:  This step tests the ability of the BARO sensor to correctly indicate barometric pressure. The value shown for the BARO sensor varies with altitude.
  2. 6:  This step tests for a sensor that is stuck in range.
DTC P2227 (Federal RPO FE9, NG1)

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) 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 OFF the ignition.
  2. Inspect the BARO sensor for a plugged port.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 3 
3
IMPORTANT: The vehicle used for a comparison is not limited to the same type of vehicle that is being serviced. A vehicle known to provide an accurate BARO reading is acceptable.
Do you have access to another vehicle in which the BARO parameter can be observed with a scan tool?		 - Go to Step 4  Go to Step 5 
4 
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the BARO sensor pressure with a scan tool.
  3. Turn ON the ignition of the known good vehicle, leaving the engine OFF.
  4. Observe the BARO parameter of the known good vehicle with a scan tool.
  5. Compare the values.
Is the difference between the values less than the specified value?		 5 kPa Go to Step 6  Go to Step 9 
5
IMPORTANT: The Altitude vs. Barometric Pressure table indicates a pressure range for a given altitude under normal weather conditions. Weather conditions consisting of very low or very high pressure and/or very low or very high temperature may cause a reading to be slightly out of range.
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the BARO sensor pressure with a scan tool. Refer to Altitude vs Barometric Pressure .
  3. The BARO sensor pressure should be within the range specified for your altitude.
Does the BARO sensor indicate the correct barometric pressure?		 - Go to Step 6  Go to Step 9 
6 
  1. Connect a J 23738-A  Mityvac vacuum pump to the BARO sensor port.
  2. Monitor the BARO sensor pressure with the scan tool.
  3. Apply vacuum SLOWLY 1 inch Hg at a time. Each inch of vacuum should result in a 3-4 kPa drop in the BARO sensor pressure.
  4. Increase the vacuum to 20 inches Hg.
Does the scan tool indicate that the BARO sensor pressure decreases smoothly through the test?		 - Go to Step 7  Go to Step 9 
7 Disconnect the hand vacuum pump from the BARO sensor port.
Does the BARO sensor pressure return to the original value that was observed in Step 4 or 5?		 - Go to Step 8  Go to Step 21 
8
  1. Observe the boost sensor pressure and the BARO sensor pressure with the scan tool.
  2. Compare the values.
  3. Is the boost sensor pressure less than the BARO sensor pressure by more than the specified value?
 10 kPa Go to DTC P0236 (California RPO YF5, NE1, and VCL) or DTC P0236 (Federal RPO FE9, NG1) Go to Intermittent Conditions
9
  1. Turn OFF the ignition.
  2. Disconnect the BARO sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
Does the scan tool indicate that the BARO sensor pressure is more than the specified value?		 44 kPa Go to Step 18  Go to Step 10 
10
  1. Connect a test lamp to a good ground.
  2. Probe the 5-volt reference circuit of the BARO sensor with the test lamp.
Is the test lamp OFF?		 - Go to Step 17  Go to Step 11 
11 Measure the voltage from the 5-volt reference circuit of the BARO sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Does the voltage measure more than the specified value?		 5.2 V Go to Step 14  Go to Step 12 
12 Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the BARO sensor and the signal circuit of the BARO sensor.
Does the scan tool indicate the BARO sensor pressure is more than the specified value?		 200 kPa Go to Step 13  Go to Step 16 
13
  1. Turn OFF the ignition.
  2. Remove the jumper wire.
  3. Connect a jumper wire between each of the terminals in the BARO sensor harness connector and the corresponding terminal at the BARO sensor. Refer to Using Connector Test Adapters in Wiring Systems.
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage from the low reference circuit of the BARO sensor at the jumper wire terminal to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems.
Is the voltage more than the specified value?		 0.2 V Go to Step 15  Go to Step 19 
14 Test the 5-volt reference circuit of the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 22 
15 Test the low reference circuit of the BARO sensor for high resistance or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
16 Test the signal circuit of the BARO sensor for the following conditions:
  • A short to ground
  • An open
  • High resistance

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
17 Test the 5-volt reference circuit of the BARO sensor for the following conditions:
  1. A short to ground
  2. An open
  3. High resistance

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
18 Test the signal circuit of the BARO sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 22 
19 Inspect the BARO sensor for poor connections. 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 23  Go to Step 21 
20 Inspect the ECM for poor connections. 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 23  Go to Step 22 
21 Replace the BARO sensor. Refer to Barometric Pressure (BARO) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 23  -
22 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 23  -
23
  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 24 
24 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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