Problems with 1994 Pontiac Bonneville

The Service Engine Soon (SES) light is controlled by the car's ECM, or computer. Whenever the ECM detects a problem, such as a sensor reading not being what it should for instance, it will illuminate the SES and under certain circumstances set a trouble code in it's memory. The SES only serves to let you know that something is wrong. There are tools and techiques for responding to a SES situation, but one thing is certain: You can easily throw $5,000 worth of parts at the car and not fix the real problem. There are no shortcuts to properly diagnosing and repairing the underlying problem.

To start, you need to see what trouble codes are stored in the ECM. I don't know the particular procedure for your car, but you should be able to take it to your local auto parts store to get the codes from the ECM. I know that AutoZone does this for free. Once the trouble codes have been retrieved you can proceed with diagnosis and testing. You will need a factory service manual for this, the aftermarket manuals like Chiltons and Haynes will not work. You will also need a digital volt meter, or DVM, to do some of the tests required. A decent DVM can be had for under $50 nowadays, just make sure that it has at least 10 mega ohms input impedence on the voltage measuring function.

Once you get the factory service manual and the trouble codes, follow the detailed charts and instructions in the manual and you should be able to correct whatever is wrong.

Remember, there are no shortcuts here. I once skipped the very first step in the chart for my car and ended up buying a $300 ECM that I didn't need.

JazzMan

Thanks for the help. I have been to Autozone and their device was unable to detect the code. I guess I'll be visiting my local dealer. My Grandfather just had his car checked and it was about $27. So I guess that will let me get started. Thanks again. Keith