OBSBible
3-second answer: RABS light on = rear anti-lock system fault, most often the rear axle speed sensor or a bad RABS module ground. The regular brakes still work — don't panic. Soft pedal = air, a leaking master/booster, or the rear proportioning valve; bleed in the right order.

Rear ABS (RABS) — the OBS quirk

F-150s and Broncos came with rear-only ABS (RABS) that loves to set the dash light: 1. The sensor lives on top of the 8.8 rear end (10 o'clock). Corrosion and gap are the usual failure — the air gap spec matters. 2. Check for codes first: jumper the diagnostic connector and watch the light blink. 3. The RABS module is behind the left kick panel. Bad grounds kill these.

Soft / low pedal

Torque specs you'll need

community-standard · verify

Complaint signal

Brakes are the #1 complaint category in NHTSA data for these trucks — 1,086 hydraulic-brake complaints, including 421 ABS/RABS (light on, rear lockup in rain/snow), 331 rotor/caliper (vibration, premature wear), 144 master-cylinder, and 75 brake-line failures (rusted lines causing total failure — check your lines). If you own one of these, the brake lines and ABS sensor are inspection items, not wait-for-failure items.

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