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Home >> Pontiac >> 1987 >> Firebird Formula, 5.0 F >> Repair and Diagnosis >> Engine Performance >> System >> 1987-88 Computerized Engine Controls >> Chart C1B - Crank Signal

Chart C1B - Crank Signal

Crank signal is a 12-volt signal to ECM during cranking to allow enrichment and cancel diagnostics until engine is running or 12 volt is no longer on circuit.

  1. Checks for normal (cranking) voltage to terminal C9 of ECM. Test light should be on during cranking.
  2. Determines if source of blown fuse was a faulty ECM.
Fig 1: Flow Chart C1B, Crank Signal
G7120
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