I have a 99 Expy, autoAWD, air ride, with 180,000 miles on it. All of the sudden it started to engage the ABS system for about the first 2-3 blocks I travel-sometimes not letting me stop! Then it goes away and brakes work normally. The ABS light does not come on.
Only thing new is I went through some heavy mud a few days ago- since then tried my best to rinse off undercarriage.

 

ok, you replied to mine so i'll reply to yours. my abs light did not always come on either, but when i first put on brakes out of the driveway that back sensor was giving out a false reading and engages my abs in the back. but then normal operation after that.

 

My 2001 f150 4x4 had ABS false triggering. It took me quite a while to fix it. The front hubs were worn causing the rotors to walk away from the ABS sensors causing the false ABS triggering. The ABS sensors are just about impossible to remove. I see your in Western PA (i'm from pittsburgh) the salt belt.

I would buy new hubs & ABS sensors. It's not cheap!

Traded my 2001 for a 2008 a few months ago.

 

I found out why there's no light- the bulb is burnt out.
I did think about a bad hub-or wheel bearing. I don't know I didn't check to see if it has bearing assembly's like a front wheel drive or regular bearings.
I was just hoping for a DUH- type thing and a quick fix- wi****l thinking! LOL
I am getting my buddy's computer to scan the ABS computer since I can't read the flashes. So far everything I encounter with this someone else (well many people)has seen it, so I know to come here first!

 

If its the hubs/bearings a ABS scanner won't show anything wrong since every thing is "working"

My mechanic buddy tells me that fords are very sensative to the hub/bearing wear. GM's arent. It's the ABS design that's very sensative to any mechanical error (wore hubs)

Good Luck

Jerry