Welcome to the forum, you'll get lots of help here.
It's likely the cruise control amp, located above and to the left of the steering shaft under the instrument cluster. It's a silver box about 4" x 5" x 1". There are a few threads regarding resoldering the circuit boards, or you can get a rebuilt/exchange for a couple hundred. It's a common failure in the 126 line. I replaced my cruise amp with one from a junkyard, and I've also tried the resolder route (unsuccessfully). A quick search will give you some results. Try "cruise control."
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