Programmable Read Only Memory (Prom): Installation

Check that new PROM has the same service number as the old one. Place the new PROM in the ECM. Position the PROM carrier squarely over the PROM. Press on the PROM carrier until the PROM is firmly seated in the ECM.
NOTE: Make sure that the reference notches in both the ECM and the PROM are properly aligned.
Reinstall PROM access cover on ECM. Reinstall ECM in vehicle as previously described. Start engine and ground diagnostic test lead. Watch for trouble Code 51.
If this occurs, PROM is not fully seated in ECM, installed backwards, has bent pins or is defective. If pins are bent and crack when straightened, PROM must be replaced. If PROM is installed backwards or is defective, it must be replaced.