DTC 51

Code 51 indicates that the calibration PROMs are not being read properly by the ECM. Possible reasons for this condition are PROMs that are installed backwards or PROMs installed with bent or missing pins. Remove cover on ECM and check to ensure that PROMs are properly installed. Refer to ``Prom, Replace'' for proper procedure. If PROMs appear to be properly installed, clear codes and turn ignition off for ten seconds. If code 51 remains, replace PROMs. Repeat procedure and, if code remains after replacing PROMs, replace ECM.