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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1073 (Engine Controls Diagnosis - 6.6L (LLY) (DTC P0238 To DTC P0652)) >> Diagnosis >> DTC P0404 >> Conditions for Clearing the MIL/DTC

Conditions for Clearing the MIL/DTC

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.
DTC P0404

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:
    • Attaching the shop exhaust system to the vehicle may cause false exhaust gas recirculation (EGR) DTCs to set.
    • Performing the exhaust gas recirculation (EGR) solenoid output control function may result in setting EGR system DTCs.
  1. Start the engine.
  2. Observe the EGR Position Variance parameter while commanding the exhaust gas recirculation (EGR) valve from 0-30 percent with a scan tool.
  3. Exit the EGR output control function.
Did the EGR Position Variance parameter read more than the specified value when commanded with a scan tool?		 6% Go to Step 4  Go to Step 3 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  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 cycle?		 - Go to Step 4  Go to Intermittent Conditions
4 Is DTC P0403, P0405, or P0406 also set? - Go to DTC P0403  or DTC P0405  or DTC P0406  Go to Step 5 
5 Test for shorted terminals and poor connections at the EGR valve. Refer to Testing for Intermittent Conditions and Poor Connections andConnector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 16  Go to Step 6 
6
IMPORTANT: Failure to follow the below procedure can result in inaccurate test results.
IMPORTANT: Direct battery voltage to the EGR valve motor is not to exceed 5 seconds.
  1. Disconnect the EGR valve.
  2. Start the engine.
  3. Measure the ignition voltage at the battery and note as supply voltage.
  4. Connect a 5-amp fused jumper between the battery positive terminal and the high control circuit terminal on the EGR valve.
  5. Setup the DMM to measure amperage. Refer to Circuit Testing in Wiring Systems.
  6. Connect a DMM between the battery negative terminal and the low control circuit terminal on the EGR valve.
  7. Measure the amperage and note as current draw.
  8. Remove the DMM and the 5-amp fused jumper wire.
  9. Divide the supply voltage by the current draw in order to calculate the resistance of the EGR valve motor coil.
Is the calculated resistance within the specified value for the specified EGR coil case temperature?		 -40°C (-40°F) 1.42-2.8 ohm
25°C (77°F) 1.62-3.2 ohm
90°C (194°F) 1.75-3.6 ohm
150°C (302°F) 1.89-4.0 ohm		 Go to Step 7  Go to Step 14 
7
  1. Measure the voltage from the 5-volt reference circuit of the EGR position sensor to a good ground with a DMM and note as "supply voltage".
  2. Connect a test lamp and a DMM in series between the 5-volt reference circuit of the EGR position sensor and the low reference circuit of the EGR position sensor.
  3. Measure the amperage and note as "current draw".
  4. Remove the DMM and connect the test lamp between the 5-volt reference circuit of the EGR position sensor and the low reference circuit of the EGR position sensor.
  5. Connect a DMM in parallel between the 5-volt reference circuit of the EGR position sensor and a good ground.
  6. Measure the voltage and note as "load voltage drop".
  7. Subtract the "load voltage drop" from the "supply voltage" and divide your answer by the "current draw" in order to calculate the resistance in the 5-volt reference circuit.
Is the calculated resistance more than the specified value?		 300 ohm Go to Step 10  Go to Step 8 
8
  1. With the test lamp still connected, connect a DMM in parallel between the low reference circuit of the EGR position sensor and a good ground.
  2. Measure and note the "low reference voltage drop".
  3. Divide the "low reference voltage drop" by the "current draw" measured in the previous step in order to calculate the resistance in the low reference circuit.
Is the calculated resistance more than the specified value?		 5 ohm Go to Step 10  Go to Step 9 
9
  1. Remove the test lamp and the DMM.
  2. Connect a jumper wire between the 5-volt reference circuit of the EGR position sensor and the signal circuit of the EGR position sensor.
  3. Observe the EGR Sensor parameter with a scan tool.
Is the voltage more than the specified value?		 4.9 V Go to Step 11  Go to Step 10 
10 Test for shorted terminals and poor connections at the engine control module (ECM). 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 16  Go to Step 12 
11
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the EGR motor high and low control circuits for high resistance. Refer to Circuit Testing in Wiring Systems.
Is the resistance more than the specified value?		 High Control Circuit = -7 ohm
Low Control Circuit = -9 ohm		 Go to Step 12  Go to Step 13 
12 Repair the high resistance in the affected circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 16  Go to Step 15 
13
  1. Remove the EGR valve. Refer to Exhaust Gas Recirculation (EGR) Valve Replacement .
  2. Inspect for debris that will cause the EGR valve to stick. Clean if necessary. Refer to Exhaust Gas Recirculation (EGR) System Cleaning .
Did you find and correct the condition?		 - Go to Step 16  Go to Step 14 
14 Replace the EGR valve. Refer to Exhaust Gas Recirculation (EGR) Valve Replacement .
Did you complete the replacement?		 - Go to Step 16  -
15 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 16  -
16
  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 17 
17 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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