- Preliminary Inspection

A careful visual and physical underhood inspection must be performed as part of any diagnostic procedure or in finding the cause of a failure. This can often lead to fixing a problem without further steps. Inspect all vacuum hoses for correct routing, pinches, cuts or disconnects. Be sure to inspect hoses that are difficult to see beneath the air cleaner, compressor, generator, etc. Inspect all the wires in the engine compartment for proper connections, burned or chafed spots, pinched wires, or contact with sharp edges or hot exhaust manifolds. This visual/physical inspection is very important. It must be done carefully and thoroughly.


All of the Diagnostic procedures have specific conditions under which each test is to be performed. Basic conditions that apply to all tests are:

^ Battery in good condition and fully charged.
^ Adequate fuel in the fuel tank.
^ Fuel is uncontaminated.
^ Maintenance components in good condition (Fuel Filter, Spark Plugs)

Read each test procedure carefully to determine additional test conditions.