Diagnostic System: Notes

The ECM of the PFI control system has a built in diagnostic capability to constantly monitor engine/vehicle performance and operation. The diagnostic system consists of 4 test: engine malfunction test, data display, input test and output test. See Fig 1 . When diagnosing PFI system, always perform tests in the order described to determine system failures in the shortest amount of time. Description of each test is as follows:

Fig 1: Identifying PFI Diagnostic System Test Parameters

Courtesy of GENERAL MOTORS CORP.