95 Windstar ABS Problem

The left front brake makes a "bonging" (if that's a word) sound occasionaly when brake pedal is applied. Have replaced caliper as car as 200,000 miles on. It started almost a year ago and I discovered a broken shock spring on that wheel and replaced it. But it did not stop the "bonging". Pads and rotors are fine as they were replaced not too long ago. I jacked up the car and pulled the wheel and had my wife step on the brake several times and every so often you could see the inside pad contacting the rotor a couple of seconds "late" making the "bong" sound.
I pulled the fuse on the ABS and it no longer "bongs". I cleaned the sensor and the ring, then replaced the fuse, but "bonging" returned. On another forum one of the respondents said what I did would ruin the control unit. I reinstalled the ABS fuse and same problem, but on a slippery MN street the ABS was working, but the "bonging" was occuring much more often.
It seems that it would narrow down to either a bad sensor or the ABS control unit. Is there a way I can test sensor and/or control unit or can it only be done by a professional mechanic? Thanks for any help you can give!

Make sure the excitor ring is ok. The gear tooth looking thing.

One of the first things I did to my 95 when I got it about 3 years ago was replace the HCU (hydraulic control unit; what you are calling the ABS control unit I believe) cause it was bad. In any case I ordered one from a junk yard that seemed good and some kind of ordering botch up happened and they ended up sending me 2 of them in two separate boxes. So if you determine its the HCU I can make ya deal for the extra one I have. All I can say up front though is that it did come from a junk yard so I have no idea of its condition and if it works, but the junk yard said it would and they even had a brief warranty on it which I thought was cool for a junk yard. The one that was installed though DID WORK fine and still is working in my 95 today.... and it'll actually be in use again once my engine debacle is over with! lol - So if you end up wanting it PM me. Otherwise like my shop told me at the time... your brakes will always work, but your ABS may suffer a bit or not work at all. As long as the ABS or Brake light isn't on you probably are ok. You may also need to flush your brake fluid... it could be really dirty. The BONG you may be hearing could be a spring in the master cylinder too although that wouldn't make sense that you'd only hear it when the ABS fuse is plugged in.

Just a thought that the previous post gave me. Could the bong sound you are hearing coming from the left front brake be coming from the abs control unit/hcu (which has a pump in it). It is located close enough to the brake/wheel that it may seem like it's the brake when it actually is the abs unit. It is under the battery and on the frame rail with a bunch of metal lines going to it.

The statement in the original post that the "bong" sound does not happen with the ABS fuse pulled leads me to believe that the sound IS the ABS system.
This is the normal sound that it makes when it activates.
I don't know that it would be the actual hydraulic unit.....something is telling it to activate.....and it is working otherwise.