pontiac firebird ecm failure.why?

Corrosion or damage due to moisture is one of the main reasons for ECM failure. Corrosion can enter the ECM through the wiring harness and moisture can enter by a failure in the seals in the ECM itself. This happens over a period of time (5 to 10 years) due to the ECMs exposure to the elements. The electronic fuel solenoid is also a main reason for failure in the ECM. The solenoid can cause a short in the ECM due to corrosion in the solenoid or the wire running from the solenoid to the ECM harness. The electronic fuel solenoid is located at the top of the fuel pump. The solenoid seems to fail due to corrosion as fast or faster then the ECM. If the car is running fine then you shut your engine off and it will not restart then this is a good indication that the starter has shorted out the ECM. The third thing that can cause failure in the ECM is the Injector wiring harness or the sensor wiring harness. Once again corrosion or breaks in the internal wiring in the harness can cause a short in the ECM or corrosion can enter the ECM through the wiring harness. Again this is caused by exposure to the elements. If your check engine light is on then you should be able to read a fault code from your ECM. The fault codes should help identify where the problem is originating from. But ECM failures occur from overvoltage, shorted outputs, and transients usually.

Personally the best way is to take it to shop and have a tech look at it for sure. P.S. if you ever decide to sell the Trans Am, I'll buy it from you To Keep In #1 Original Condition :-)

hi, thanks for the response.I have checked the wiring harness,inside the car and out and cannot see anything obvious.however,the alternator has died.[this has been checked by 2 different places] neither can get any reading out of it so it musyt be pretty severe. also the charcoal canitster purge solanoid is not working [seized] this ,i believe is on the same quad driver that has blown.not quie sure what to do next i am now waiting for the alternator to come back from being re built.but i am having no end of trouble getting someone to plug the car in [i am uk based]although the "check engine" light is on when the ecm failes it will no longer flash the trouble codes presumably this is on the circuit that has gone..once again,thanks for the reply.will keep you posted. MARK.+[ a very poorly] K.I.T.T.

It's good mark, probably being UK based you might not have all The places we have here for parts of the F-body or mechanics that are used to having so many come In. But yes keep me posted, if you ever want to part with it, I'll be glad to turn it into a Showroom K.I.T.T. that will make jaws drop :-)