Cadillac Repair: HELP!, wiring schematics, cadillac sedan deville

Question
I have a 94 Cadillac Sedan Deville.  I bought it less than 2 years ago.  Since then I had a 92 Deville 4.9 L engine put in and a new trans. it hasn't ran right since.  I moved to California and need a smog, it would not pass.  I have replaced the plugs, wires, rotor, cap, distributor and all codes are clear.  It still will not pass and now has a hard time starting and runs worse than when I brought it to the shop.  I also have a new battery and starter.  Any suggestions?    Will a 92 Deville engine have trouble with a 94 Deville Prom/ ECM?  So in summary after all of this my car is still not right, it stalls, has a slight ping and starts really rough?   I am at my end and my mechanic is at a loss.  Will putting a 92 PROM in it fix the problem? Please help!!!!

Answer
You stated: "Will a 92 Deville engine have trouble with a 94 Deville Prom/ ECM". ABSOLUTELY.

Also the ECM's are DIFFERENT and  alot of the wiring that goes to the ECM plugs are loacted in DEFFERENT places within the electrical connectors.

lets say that in the BLUE ecm connector there is a YELLOW wire in pin location A10 for the 92 vehicle.

In this SAME pin location there may be a GREEN wire for the 94 vehicle.


You have to check EACH AND EVERY WIRE and compare them from the 92 to the 94 wiring schematics as you will soon find out that there are NUMEROUS differences in which wires go where.



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