You guys are right, rear speed sensor on the diff.

I did a bunch of research yesterday. For the record, I found the F250 uses the Kelsey-Hayes EBC10 ABS system. Two sensors on the front on each steering knuckle and one on the top of the rear diff. Apparently, bad sensors and/or sensor connectors cause ABS probs 9 outta 10 times on the trucks.

I went home and pulled and cleaned my front sensors and connectors last night and checked 'em OK. I only cleaned the rear connector, I didn't bother to pull it or check it's resistance. Didn't help the problem tho.

The ABS module provides codes but have to be scanned. This morning a really nice guy at a local francise brake shop, Brake Chek, read mine for free and confirmed the rear sensor problem. Whatta guy. Local dealer wanted $98 just to scan the code. What a rip-off. I think $20 to do a scan would be ok but $98!!!

Come to find out the rear sensor seems to fail the most. The sensors are magnetic. You can check'em with a voltmeter and you should get somewhere between 700 and 2K ohms. If they're open or shorted, they're bad.

The rear speed sensor was $19 at the dealer. I can't wait to get home and replace that baby tonight.

Regards