CAUTION: Diagnosis by substituting a component from another vehicle is NOT allowed. Substitution of control modules does not guarantee confirmation of the fault and, in addition, may cause additional faults in the vehicle being tested and/or in the vehicle from which the modules are removed.
1. Visually inspect for obvious signs of mechanical and electrical damage.
Mechanical factors | Electrical Factors |
2. If an obvious cause of the problem you identified or the customer described is found, resolve it before proceeding to the next steps (if possible).
3. If the cause is not visually obvious, check the symptom and contact symptom table or check for DTCs and refer to the Index diagnostic trouble codes (DTC).
NOTE: For all vehicles equipped with a fuel tank leak diagnostic unit (DMTL), it is required to install a plug in the vent (in a large diameter pipe) DMTL unit to prevent misdiagnosis during emissions testing.
4. Where K-Line, Vacutec, or other branded emissions testing equipment is available, it should be used to test the fuel vapor recovery system for leaks.
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