Cadillac Repair: 1990 deville codes, negative battery cable, ohmeter

Question
Hi i have a question. my caddy runs rough when driving and sitting. A neighbor pulled up codes and it read "e52 .7.0" . what does this mean? the only thing i can find is pcm/ecm battery disconnect problems on the internet but i dont think this is the problem. can you help?

Answer
Hi Chris,

     The E52 means that the ECM lost power or the battery was disconnected. The .7.0 means that all the codes have been displayed.  

      Where I would start with this problem is look at the plugs, cap rotor and wires to see their condition and replace as needed. If the plugs have more than 30,000 miles on them and the other parts more that 75,000 then doing a complete tune-up might solve the running problem.

       If the problem persists then negative battery cable will need to be removed from the engine and both sides of the terminal sanded as well as the engine block before bolting it back up.

       On an older engine the fuel injectors could be shorted and need to be replaced. I would use an ohmeter and remove all the injector connectors and replace any that are more than 1 ohm differance that the rest. I believe that a normal injector is around 12 ohms and it wouldn't surprise me if you had 3 or more injectors shorting.

       Of course there are other sensors that can cause rough running but start with those things and see what happens. Let me know if you need anymore help. Bill