Code 51: Prom
Code 51 sets if any of the following occur:
- Faulty PROM unit.
- PROM unit improperly installed (may not set a code if installed backward).
- Some PROM pins not making contact (i.e. bent).
Always check to see that the PROM pins are not bent and inserted properly into ECM. Make sure the PROM is installed in the proper direction as shown in the chart. Check that all pins are fully inserted in the socket. If okay, replace PROM and recheck. If problem not corrected. Replace ECM.
Small notch of carrier should be aligned with small notch in socket. Press on PROM carrier until it is firmly seated into the socket. Do not press on PROM; only the carrier.