Test Description

The numbers below refer to the step numbers on the diagnostic test procedures.

1. 1
   
   Any DTCs set may prevent the required DTCs from running. If there is any question as to whether a set DTC is disabling the required I/M diagnostic, review the Conditions for Running in the diagnostic procedures for the DTC required by the I/M diagnostic.
2. 2
   
   Anytime a control module is reprogrammed or the diagnostic trouble codes are cleared as part of a repair procedure, all the I/M System Status indicators will reset to NO.
3. 3
   
   This step is to determine if the system status that was not complete is in the PCM or AF ECM.
4. 4
   
   Removing the fuse for the AF ECM will force the vehicle to run on gasoline. Once the vehicle is running on gasoline, the set procedures for gasoline fueled vehicles can be used to set the I/M System Status to YES. Use discretion when determining whether the entire I/M Complete System Set Procedure needs to be performed. For example, if the only tests that have not run are those that require the engine to be at operating temperature, then only those individual tests need to be run. There is no need to allow the engine to completely cool in order to run these tests. Removing the CNG fuse will reset the I/M System Status in the CNG controller to NO.
5. 5
   
   Reinstalling the fuse for the AF ECM will restore CNG operation.
6. 6
   
   This step is to determine if a system status is not complete in the AF ECM.