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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1063 (Engine Controls Diagnosis - 6.6L (LLY) (DTC P0016 To DTC P0237)) >> Diagnosis >> DTC P0181 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. 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. 2:  This step determines if the IAT sensor is within the normal range. If the value is outside of the specification, the IAT sensor may be inaccurate or the circuit may have high resistance.
  2. 4:  This step determines if the fault is present at the time of diagnosis.
  3. 15:  Reprogram the replacement ECM. Refer to the latest techline information for ECM programming.
DTC P0181

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 
IMPORTANT: The intake air temperature (IAT) sensor will start to warm-up as soon as the ignition is turned ON.
  1. Allow the engine to cool to ambient temperature by comparing IAT and engine coolant temperature (ECT) parameters.
  2. Record the ambient air temperature surrounding the vehicle using an accurate thermometer.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the IAT parameter with a scan tool.
Does the scan tool indicate a temperature close to the ambient air temperature, within the specified range?		 10°C (18°F) Go to Step 3  Go to Step 5 
3
  1. Observe the Fuel Temperature Sensor parameter with a scan tool.
  2. Observe the IAT Sensor parameter with a scan tool.
Is the difference between the Fuel Temperature Sensor parameter and the IAT Sensor parameter more than the specified value?		 10°C (18°F) Go to Step 7  Go to Step 4 
4 
  1. Start the engine.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC fail this ignition?		   Go to Step 5  Go to Diagnostic Aids
5
  1. Disconnect the mass air flow (MAF)/IAT sensor connector.
  2. Turn ON the ignition with the engine OFF.
  3. Measure the voltage from the IAT signal circuit at the MAF sensor harness connector to a good ground with a DMM. Refer to in Wiring Systems.
is the voltage measured within the specified range?		 4.9-5.1 V Go to Step 6  Go to Step 8 
6
  1. Turn OFF the ignition.
  2. Wait approximately 60 seconds or until the engine control module (ECM) powers down.
  3. Measure the resistance from the low reference circuit of the IAT sensor harness connector to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the resistance less than the specified value?		 5 ohm Go to Step 13  Go to Step 11 
7
  1. Disconnect the air filter outlet duct to access the fuel temperature sensor.
  2. Disconnect the fuel temperature sensor harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the fuel temperature sensor signal circuit to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
is the voltage measured within the specified Range?		 4.9-5.1 V Go to Step 9  Go to Step 10 
8
  1. Turn OFF the ignition.
  2. Disconnect the ECM connectors.
  3. Test the IAT signal circuit for the following conditions:
Did you find and correct the condition?		 - Go to Step 18  Go to Step 14 
9
  1. Turn OFF the ignition
  2. Wait approximately 60 seconds or until the ECM powers down.
  3. Measure the resistance from the low reference circuit of the fuel temperature sensor harness connector to a good ground with DMM. Refer to Circuit Testing in Wiring Systems
Is the resistance less than the specified value?		 5 ohm Go to Step 12  Go to Step 11 
10 Repair the high resistance in the fuel temperature sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 18  Go to Step 14 
11 Repair the open or the high resistance in the sensor low reference circuit. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 18  Go to Step 14 
12 Inspect the fuel temperature sensor for any of the following conditions:
Did you find and correct the condition?		 - Go to Step 18  Go to Step 17 
13 Inspect the MAF/IAT sensor for any of the following conditions:
Did you find and correct the condition?		 - Go to Step 18  Go to Step 16 
14 Test for intermittent and for poor connections at the ECM connector terminals. Repair as necessary. 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 18  Go to Step 15 
15  Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 18  -
16 Replace the MAF/ IAT sensor. Refer to Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 18  -
17 Replace the fuel temperature sensor. Refer to Fuel Rail Temperature (FRT) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 18  -
18
  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 19 
19 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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