The check engine light coming on tells you that the ECM is seeing something it doesn't like !! The ECM will leave a code for the problem or 2 !! You can get the codes without the scan tool or you can go to one of those local auto parts store that will scan it for free!
You can do it with just a simple paper clip. Locate the ALDL (Assembly Line Diagnostic Lead). It is usually under the drivers side of the dash. It may have a cover over it, and may even say "Diagnostic Connector".
This is the ALDL. The two terminals that you need to be concerned with is in the picture. It is terminals "A" and "B". Simply turn the Ignition to "Run" (Do not start the vehicle) and put the paper clip in the two terminals. Now watch your CEL. It will start flashing. It will look like Morse Code, but it isn't, and is real easy to interpret.
The first code that will flash will be a code 12. It will be "flash, pause, flash, flash, pause, pause," and repeat the cycle three times. The ECM will flash each code three times, and move on to the next. If you have no codes stored, it will keep flashing code 12. Code 12 simply tells you the ECM is not receiving any pulses from the distributor (since the car is not running). If you pull codes with a scantool and the car is running, this code will not show up. Its no big deal, it lets you know the ECM is in the "Field Service Mode" You will also notice the cooling fans come on, this is normal.
