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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1022 (Engine Controls Diagnosis - 6.6L (Lb7) (DTCS P0612 To P2141)) >> Diagnosis >> DTC P1172 >> 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. 3:  This step determines if the condition is on the coil side, or the switch side of the fuel pump relay.
  2. 11:  This step verifies the fuel transfer pump operation. If the test lamp flashes, then the fuel transfer pump and circuits are OK.
  3. 16:  This step tests for a fuel flow condition.
DTC P1172

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
1 Did you perform the Diagnostic System Check-Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 Is DTC P0461, P0462, P0463, P2066, P2067, or P2068 also set? - Go to Diagnostic Trouble Code (DTC) List in Instrument Panel, Gages, and Console Go to Step 3 
3 
IMPORTANT: The fuel level must be between 25-50 percent in order to perform this diagnostic procedure. If the fuel level is not within this range, misdiagnosis will occur.
  1. Turn ON the ignition, with the engine OFF.
  2. Command the fuel pump relay ON and OFF with a scan tool.
Does the fuel pump relay click?		 - Go to Step 9  Go to Step 4 
4
  1. Remove the fuel pump relay from the underhood electrical center.
  2. Probe the ground circuit of the fuel pump relay with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors and Circuit Testing in Wiring Systems.
Does the test lamp illuminate?		 - Go to Step 5  Go to Step 22 
5
  1. Probe the fuel pump relay control circuit with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
  2. Command the fuel pump relay ON and OFF with a scan tool.
Does the test lamp turn ON and OFF?		 - Go to Step 19  Go to Step 6 
6 Does the test lamp remain illuminated? - Go to Step 7  Go to Step 8 
7 Test the fuel pump relay control circuit 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 28  Go to Step 26 
8 Test the fuel pump relay control circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 28  Go to Step 21 
9 Command the fuel transfer pump ON with a scan tool.
Does the fuel transfer pump operate?		 - Go to Step 14  Go to Step 10 
10
  1. Remove the fuel pump relay from the underhood electrical center.
  2. Turn ON the ignition, with the engine OFF.
  3. Probe the ignition 1 voltage circuit of the fuel pump relay with a test lamp that is connected to a good ground.
Does the test lamp illuminate?		 - Go to Step 11  Go to Step 24 
11  Probe the fuel transfer pump supply voltage circuit with a test lamp that is connected to battery voltage.
Does the test lamp flash?		 - Go to Step 19  Go to Step 12 
12 Test the fuel transfer pump supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 28  Go to Step 13 
13 Probe the ground circuit of the fuel transfer pump with a test lamp that is connected to battery voltage.
Does the test lamp illuminate?		 - Go to Step 20  Go to Step 23 
14 Observe the fuel level sensor rear tank parameter with a scan tool.
Is the voltage more than the specified value?		 1 V Go to Step 16  Go to Step 15 
15 Add the specified amount of fuel to the fuel tank.
Did you complete the action?		 19 L (5 Gal) Go to Step 16  -
16 
  1. Command the fuel pump ON with a scan tool.
  2. Observe the rear fuel level sensor voltage parameter with a scan tool.
Does the rear fuel level sensor voltage decrease as the fuel pump is operating?		 - Go to Step 17  Go to Step 18 
17
  1. Disconnect the outlet hose from the fuel transfer pump.
  2. Connect a section of rubber hose with a clamp to the outlet port of the transfer pump.
  3. Insert the other end of the rubber hose into a container to measure hose into a container to measure more the 4.0 Liters (1.06 gallons).
  4. Operate the transfer pump with a scan tool for a total of 120 seconds.
  5. Measure the fuel in the container.
Does the fuel volume measure more than the specified value?		 2.6 L (0.70 gal) Go to Intermittent Conditions Go to Step 18 
18 Inspect for the following conditions:
  • A restriction in the fuel lines between the front and rear fuel tanks
  • The rear fuel sender for a restriction

Did you find and correct the condition?		 - Go to Step 28  Go to Step 26 
19 Inspect for poor connections at the harness connector of the fuel pump relay. 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 28  Go to Step 25 
20 Inspect for poor connections at the harness connector of the fuel transfer pump. 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 28  Go to Step 26 
21 Inspect for poor connections at the harness connector of the 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 28  Go to Step 27 
22 Repair the open ground circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
23 Repair the open ground circuit of the fuel transfer pump. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
24 Repair the open ignition 1 voltage circuit of the fuel pump relay. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 28  -
25 Replace the fuel pump relay.
Did you complete the replacement?		 - Go to Step 28  -
26 Replace the fuel transfer pump. Refer to Fuel Pump Replacement (Cab/Chassis) .
Did you complete the replacement?		 - Go to Step 28  -
27 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 28  -
28
  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 29 
29 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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