OK my engine is running like crap. I backfires sometimes and it misses all the time. I checked all the plug wires and the entire ignition is new. I used to have a Check engine light however it no longer works. I did the diagnostic and the fan turns on but the check engine light does nothing. I checked the bulb and it is fine. The lights around it work fine so i dont think its the circuit. How long does the ECM last? How would I know if its fried? I have a 85 Z28 TPI.

 

Agent-Z,

Does the MIL not work at all, even when the ignition is first turned on?

If not, you have the option of using an aftermarket code scanner or rigging a test light or meter to scan for codes (Ford EEC-IV method).



Connect one lead of a 12V test light (or voltmeter set at an appropriate scale for 12VDC) to a positive voltage source and the other lead to terminal 'D' of the ALDL connector. Ground the diagnostic request terminal 'B' and watch the test light or meter just as you would the MIL on the dash. If you cannot display any codes via that method, I would suggest removing and reseating the connectors on the ECM and trying it again. If the connections and ECM power and ground are O.K., you may be one of the "lucky" few who has a failing ECM.