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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 351 (Engine Controls Self-Diagnostics - 2.2L Bi-Fuel) >> Diagnostic Tests >> DTC P0148: Alternative Fuel Enable Control Circuit >> Test Description

Test Description

WARNING: This page is about a different car, the 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers in the diagnostic procedure.

  1. 2  - This step determines if the condition is active.
  2. 4  - This step determines if the PCM can control the AF relay. Command the relay ON and OFF several times to verify AF relay operation.
  3. 5  - This step tests the voltage circuit to the AF relay coil. If the test light illuminates the circuit is okay.
  4. 6  - This step tests the AF enable output circuit from the PCM. The test light should turn ON and OFF with each command.
  5. 7  - This step determines if a ground is constantly applied to the AF enable output circuit.
  6. 10  - This step tests the voltage circuit to the AF relay switch. If the test light illuminates, the circuit is okay. If the test light does not illuminate, a short to ground may be the cause of the condition. If the AF relay fuse is open, test all of the related switch circuits.
  7. 11  - This step tests the AF enable signal circuit from the AF relay to the FICM. The test light should turn ON and OFF using the scan tool commands.
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