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Home >> GMC >> 1991 >> Forward Control 6.2 J, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Chart A-4, Injector Circuit Diagnosis >> All Except 2.5L & Models W/4L80-E Transmission >> Test Description

Test Description

  1. 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.
  2. This step tests for 12 volts to injector. It will also determine if there is a short to voltage on ECM side of circuit.
  3. This test checks for continuity to ECM.
Fig 1: Chart A-4 Schematic, Injector Ckt Diagnosis (All But 2.5L & 4L80-E Equipped Models)
G50J15874Courtesy of GENERAL MOTORS CORP.
Fig 2: Flow Chart A-4, Injector Circuit Diagnosis (All But 2.5L & 4L80-E Equipped Models)
G50A15875Courtesy of GENERAL MOTORS CORP.
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