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Home >> GMC >> 1990 >> Forward Control 3.9 L >> Repair and Diagnosis (Single Page) >> Engine Performance >> Remove, Overhaul & Install >> Engine Controls - Remove/Install/Overhaul >> Electronic Control Module (ECM) >> Programmable Read-Only Memory (Prom) >> Removal
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Programmable Read-Only Memory (Prom): Removal

  1. Remove ECM from vehicle as previously described. Position ECM so that bottom cover is facing upward. Remove slide-off PROM access cover by depressing locking tab.
  2. Using PROM removal tool, grasp PROM at narrow ends. Gently rock PROM from end to end while pulling up. If new PROM is to be installed, remove old PROM from PROM carrier.
NOTE: Note reference notch locations in PROM, carrier and ECM for reassembly reference.
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