Advance Trac light Intermittent & Big Thunk in rear

[RASCARS]

I own a 2005 Lincoln LS V8 with 111,000 miles on it.

Recently the Advance Trac-traction control light will come on for no reason. When I push the console button-to disengage the Advance trac-nothing happens.
However, if I shut the car off, and restart it, the light goes out. Most often the light will stay out for a few days. Once in a while it will light up in a mile or so. Again, this is intermittent.

I did hear a big thunking sound from the rear end the other evening upon a hard acceleration. I do not know if this is related. Both the loud thunk-almost like someone has hit the back of the car- and the advance trac light have occurred before; never together though.
Does anyone have any ideas what may be causing the advance trac light to act this way? Is this a major issue? Is it expensive to fix?

Any idea what the thunk is from? Can this be fixed? It is a major issue?

I do enjoy my car, but if I am heading into a major repair bill or bills, it may be time to look for another car.

I would be very grateful for any information anyone can supply about these issues.

Thank you!

And Happy Holidays!!

[joegr]

AdvanceTrac light without ABS light = Steering wheel angle sensor, YAW sensor, or uncalibrated module. A Ford specific scan tool can tell you which.

Often it is the steering wheel angle sensor. They get dirty. Sometimes you can fix it by cleaning it.

Clunk in the rear - look at all the bushings and links back there. If you haven't replaced your rear toe links and rear sway bar links yet, I promise that you need to.

[RASCARS]

I will take the car to the dealer for the "plug in". Thank you so much.
As for the rear bushings , toe links and sway bar links-how expensive is this repair. I have not done anything with the rear yet. I did replace one from link on one side on the front last year and it was $600 at the dealer. I am trying to get another 20K miles out of the car( about 6 to 7 months) and then trade out for something CPO-MKZ, Fusion, Taurus-haven't narrowed much more that that thus far.

[shorod]

For the clunk in the rear, don't forget to also check for loose items in the spare tire well.

-Rod

[RASCARS]

Well, I took the car to 2 dealers-one Ford and one Lincoln. The Ford dealer told me I needed a Yaw sensor; installed price $851! They also said that I needed about $2,500 in suspension bushings and ends. I took the car to Car Max to get a value-$2,500 LOL. I’ll keep the car.
Since then, I did nothing to the car except drive it 2,400 miles round trip this week to visit family up north for the holidays and the car ran flawlessly.
Today, I took the car to the Lincoln dealer that I normally use and had the oil changed and asked them to check the suspension bushings and ends. It is a miracle! Nothing needs to be replaced AND the Advance trac light hasn't come on since the Ford dealer looked at the car and priced the replacement.
I hope I can drive the car for another year or two ( 25K to 45K miles) without major incident. If so, there may be a very nice CPO Lincoln MKZ in my future,
Thank you all for your help and feedback.
Happy New Year!!!