What it means
The ABS/ESC module sees the RF wheel-speed signal out of expected range (implausible, intermittent, weak amplitude) versus vehicle speed and other wheels; distinct from a simple open/short fault. Typical causes include weak sensor signal, excessive air gap, encoder damage, or wiring introducing high resistance/noise. Crypton+2Chevrolet Forum+2
Symptoms
- ABS lamp on; traction/stability control may be limited or disabled.
- Possible low-speed ABS pulsation due to noisy signal. Chevrolet Forum
Common causes
- RF sensor marginal output (contamination, incorrect seating/air gap).
- Damaged encoder/tone ring (cracked, rust-jacked, missing segments).
- Harness/connector resistance or intermittent opens near the knuckle. Chevrolet Forum+1
Diagnostic notes
- Compare live wheel-speed data; RF that drops out or reads implausibly vs. other corners indicates performance fault.
- Scope the signal; inspect encoder surface and sensor seating depth. Chevrolet Forum
Possible fixes
- Clean/reseat or replace RF sensor; correct air gap.
- Replace hub/bearing if encoder is damaged.
- Repair wiring/connector issues at the knuckle/intermediate junction. Chevrolet Forum