Programmable Read Only Memory (Prom): Installation
- Place PROM in clear carrier upside down on flat surface with pins facing up. Using a narrow blunt tool, press PROM body down on both sides of retainer bar so top of PROM is flush with top of carrier. Repeat procedure for PROM mounted in green carrier. See Figure.
- Position clear PROM carrier squarely over PROM socket in ECM. Firmly press down on top of carrier. While holding carrier down, press body of PROM down with a blunt tool. Alternately pressing down on either end will securely seat PROM. Repeat procedure for PROM mounted in green carrier.
- Install access cover on ECM and ensure it locks in place. Install ECM in vehicle. Start engine, enter diagnostics and check for code "51". If code "51" does not appear, PROM installation is correct. If code "51" is displayed, one or both PROM's are not fully seated, installed backwards, have bent pins or are defective.
- If pins are bent, straighten pins and reinstall PROM. If pins break or crack during straightening process, replace BOTH PROM's. If PROM's are installed backwards, replace BOTH PROM's.
NOTE:
First generation ECM's are not able to recognize an improperly seated PROM and cannot set a code "51". Poorly seated PROM's on first generation ECM's may produce these symptoms; Display of false codes which cannot be cleared, erratic cycling of various lights and components, or a "Hard Failure" code "74".