Test Description

This test will determine if ignition module is generating a reference pulse, if wiring is at fault or if ECM is at fault. By touching and removing a test light, connected to 12 volts, to circuit 430, a reference pulse should be generated. If injector test light blinks, ECM and wiring are OK.
This step tests for 12 volts to injector. It will also determine if there is a short to voltage on ECM side of circuit.
This test checks for continuity to ECM.

Fig 1: Chart A-4 Schematic, Injector Circuit Diagnosis (2.5L)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Flow Chart A-4, Injector Circuit Diagnosis (2.5L)

Courtesy of GENERAL MOTORS CORP.