ECM Programmable Read Only Memory (Prom): Installation
- Place new PROM in carrier upside-down on flat surface (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 the top of the PROM carrier.
- Position PROM carrier squarely over PROM socket in ECM. Firmly press down on top of carrier. Alternately pressing down on either end of carrier will securely seat PROM. Install PROM access cover. Install ECM in vehicle.
- Start engine, enter diagnostics and check for code "51/E51". If code "51/E51" is displayed, PROM is not fully seated, installed backwards, has bent pins or is defective.
- If not fully seated, remove access cover and press firmly on carrier. If pins are bent, remove PROM, straighten pins and reinstall. If pins break or crack during straightening, replace PROM. If PROM was installed backwards, it must be replaced.
- If code "51/E51" does not appear, PROM installation is probably correct. However, some pins will not set a code "51/E51", even if not making proper contact. If performance is poor, there is a blank or erratic fuel data panel, idle or part throttle surges, loss of cruise control or similar symptoms are encountered, check for a poorly seated PROM.
- On FWD DeVille and Fleetwood, PROM installation can be checked: Turn ignition on and enter diagnostics. Code "E52" should be present. If code "E51" is present, PROM installation is not correct.