LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1170 (Engine Controls Diagnosis - 6.0L - Alternative Fuels (DTC P0005-DTC P2665)) >> Diagnosis >> DTC P0148: Incorrect Fuel Mode >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet 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 condition is active.
  2. 4:  This step tests for a short to ground on the AF enable circuit.
DTC P0148

Step Action Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Fuel Injection Control Module Connector End Views
1 Did you perform the Diagnostic System Check Alternative Fuels - Engine Controls? Go to Step 2  Go to Diagnostic System Check - Alternative Fuels (Engine Controls)
2 
IMPORTANT: Verify that there is adequate fuel in the CNG fuel tank before proceeding.
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the Fuel Mode Command parameter with a scan tool.
Does the scan tool display ALT FUEL?		 Go to Step 3  Go to Step 4 
3
  1. Observe the Freeze Frame and/or the Failure records data 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 and/or the Failure records data.
Does the DTC fail this ignition cycle?		 Go to Step 4  Go to Intermittent Conditions
4 
  1. Turn OFF the ignition.
  2. Disconnect the fuel injection control module (FICM). Refer to Fuel Injection Control Module Replacement .
  3. Probe the AF enable circuit with a test lamp connected to B+.
Does the test lamp illuminate?		 Go to Step 7  Go to Step 5 
5
  1. Turn ON the ignition.
  2. Command the AF enable circuit ON and OFF with a scan tool.
  3. Observe the test lamp.
Does the test lamp respond to the scan tool commands?		 Go to Step 9  Go to Step 6 
6 Test the AF enable circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.
Did you find and correct the condition?		 Go to Step 12  Go to Step 8 
7 Test the AF enable circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.
Did you find and correct the condition?		 Go to Step 12  Go to Step 10 
8 Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.
Did you find and correct the condition?		 Go to Step 12  Go to Step 10 
9 Test for an intermittent and for a poor connection at the FICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the C/K Pickup Service Manual.
Did you find and correct the condition?		 Go to Step 12  Go to Step 11 
10 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in the C/K Pickup Service Manual.
Did you complete the replacement?		 Go to Step 12  -
11 Replace the FICM. Refer to Fuel Injection Control Module Replacement .
Did you complete the replacement?		 Go to Step 12  -
12
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  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 13 
13 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
scientia non olet · About LEMON Manuals