Before performing Symptom diagnosis
| Before performing
Symptom based diagnosis you must perform the
Diagnostic System Check - Alternative Fuels (Engine Controls)
.
The System Check will determine the following:
| • | The AF ECM, PCM and the MIL are operating correctly. |
| • | There are no DTCs stored. |
| • | Scan tool data is within normal operating range. |
Several of the Symptom diagnostic tables require that a Visual and Physical
Check be performed. Always perform a Visual and Physical Check before using
a Symptom diagnostic table.
|
Visual and Physical Checks
|
| • | Inspect the AF ECM and PCM ground connections for being clean,
tight and in the correct location. |
| • | Inspect the PCM for the correct CNG calibration. Program the PCM
if necessary. |
| • | Inspect the vacuum hoses for leaks, restrictions and proper connection
as shown on the vehicle emission control information (VECI) label. |
| • | Inspect for any type of fuel leak or fuel line restriction. |
| • | Inspect for air leaks at all areas of the intake manifold sealing
surfaces. |
| • | Inspect the ignition wires for the following conditions: |
| • | Inspect vehicle wiring for the following: |
|
