I have a 1988 Ford Thunderbird with a 3.8 engine, the check engine light keeps ing on, I've had it in to fi?

Yes, disconnecting the battery will work to clear the code. But first read out the error code.

Now here are directions on how to do this on another ford product:

http://www.ehow.com/how_7490797_diagnose-1988-ford...

Sometimes a spade fuse will work for a jumper (I can't remember if it does on this car).

Young pups don't know this trick to retrieve error codes as it predates OBDII.

I've owned several 1988 Thunderbirds. Most of them had the issue of the check engine light coming on . Most of the time it was nothing. Overall the best advice is to remove the bulb behind the dash. The dash really isn't difficult to remove.

That will clear the codes until the malfunction happens again.

it probably needs new cats..