I have a code 1660 on my 1998 Cadillac deville how do I fix it

Question

My abs light was on and my traction control light, found that a plug was unpluged near my rear drivers side tire. Plug it back in the abs light went off the traction light went off. That ment that I was able to turn the traction on and off.

But a new message came on, service sterring system....why did that come on and how do I resolve the problem of the service sterring system?