Check Engine Light?
 

I have a 1990 GXL that I recently rebuilt. It runs and drives well, but it has trouble starting cold. The check engine light is lit up on the cluster and I was wondering, is the car too old to be hooked up to a code reader? If so, what's the procedure to get the error code? (Or, if you could help with the starting issue, that'd be great too.)

Thanks!

sorry to jack but since im a noob you just stick a wire into the green plug and place it on the neg terminal for the battery?

And turn the key to on and observe for possible error codes. This specific method is for S5's while the procedure is a bit different for an S4.