Chart C-1A, Park/Neutral Switch - PFI

1987 Pontiac Firebird Formula, 5.0 H, AutomaticSECTION Chart C-1A, Park/Neutral Switch - PFI

Contacts for park/neutral switch are a part of neutral/start switch and are closed to ground in Park or Neutral, and open in drive ranges. The ECM supplies ignition voltage through a current limiting resistor to circuit No. 434 and senses a closed switch when voltage on circuit No. 434 drops to less than one volt. The ECM uses the park/neutral switch signal as one of the inputs to control vehicle speed sensor diagnostics.

Fig 1: Chart C-1A, Park/Neutral Switch - PFI
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