Cadillac Repair: cadillac 1983 deville ht4100 dfi, digital fuel injection, tiny teeth

Question
hello a code 30 came up on my car i believe it says its a isc circut problem.  so what do i do next?  what does this really mean.  hope you can help. thank you   1983 cadillac deville ht4100 w/digital fuel injection  

Answer
Hi Pat, You are right that the E30 means there is a problem with the idle speed control motor or its adjustment. Inside the motor there is a switch that tells the computor when your foot is off the gas and that could be bad. Also there are some  gears with tiny teeth that get worn and then eithor make noise or the motor will move slow. If you hear grinding when the motor moves then replaceing and adjusting the motor will probably keep the code away. If you just had a tune-up or other engine work and then the code set then the work may have been done incorrectly or the tech just forgot to clear the code. EE30 means the problem is happening right now and E30 means the code happened on some previous drive or key on. I would start by clearing the code and see if it returns. If it does and the motor is noisy then I would replace and adjust it and clear the code again. If it doesn't come back then I wouldn't worry about it until such time that the code resets and then maybe take it to your mechanic for a diagnosis or you could follow a trouble tree in a shop manual and repair it yourself. Hope that helps. Bill