ABS keeps buzzing but doesn't actually affect braking

[Therealsmitty]

So my 2003 Yukon XL has a buzz/vibration in the brake pedal when I start up, but also sporadically afterwards. I believe the first instance is the ABS self-check, but after that it'll do it again at random, anywhere from 1 to 5x. It seems to stop after all systems are good and warm. When it's still cold, I can trigger it by pushing on the brake pedal hard.
The funny thing is that it doesn't actually impact braking if it happens when I'm stopping. This part confuses me.
I have no lights on on my dash. No codes. Brake fluid is full.
I did open up the abs module (what a pain) and resolder the contacts and reinstall; no difference even though there were indeed cracks in the solder.
My next bet is to check the voltage on each hub sensor/magnetic pickup, but again, I would expect to actually feel the abs kicking in if that was the case, but all I feel and hear is a fine vibration in the brake pedal while the braking itself is totally unaffected. The other thing that leads me to believe it's not the hub sensors is that it'll still vibrate more than once while parked if I don't drive off right away. In that instance the sensors have no reason to even send a signal since the wheels haven't even turned yet.

Any ideas? I did a search on the forums to no avail unfortunately.
Thanks all.

 

[Therealsmitty]

I should also add that it's a very fine vibration, not quite like ABS that's more of a random grinding, but much more like an electric buzz that's very uniform. I imagine it's the abs doing something that's similar to activating the abs but without actually engaging any of the brake lines.

 

[Therealsmitty]

Nobody eh? I kinda figured... the abs on these trucks seems to be a real mystery sometimes.

 

[Doubeleive]

you need to hook it up to a scanner and get a live data feed to determine what is really happening

 

[bottomline2000]

I had a bad relay in my abs module in addition to the random abs/brake lights coming on. My abs pump would run after turning the truck off and the only way to get it stop was to pull the abs relay. The problems stopped after having the abs module resoldered and relay replaced. Been over 4 years since fix.

You and another guy are having similar problems and both have threads going.

https://www.tahoeyukonforum.com/threads/abs-brake-light-fix.47509/page-2
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