Diagnostic Aids:
The ECM uses the PROM information for fuel, spark, emissions and cruise systems control. If PROM is missing or unreadable, the ECM looks to CALPAK for controlling information.
The CALPAK is a resistor network whose only function is to provide "FAILSOFT" or "BACKUP" control information so that car remains driveable with a failed PROM. If CALPAK is missing or mis-installed, the vehicle will operate normally using PROM values for control. If both PROM and CALPAK are missing or unreadable, the vehicle will not start or run.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- If PROM is installed backwards, the PROM will be destroyed the first time that the ECM is powered up with backwards PROM.
- If PROM is not seated in socket, ECM may not make contact on all PROM pins.
- Check for proper PROM part number and for proper service parts packaging. Non-DFI PROM's and BCM PROM's will not function in a DFI ECM.
- Check for defective PROM or ECM. IF PROM replacement does not correct code "EO51", ECM can not read PROM. Replace ECM.