Network, generic

U04BB Invalid Data Received From Switch Input Module B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U04BB concerns the second switch input module. A receiving controller still hears module B on the bus, but the switch information inside its frames fails the plausibility, counter or checksum test. Where buttons are split across several housings, a modular layout like the one in a BCS Automotive Interface Solutions patent is typical: a main module identifies each attached satellite by a coded type and translates its signals for the CAN or LIN bus. A satellite reported with the wrong type or a coding mismatch after a part swap can produce exactly this kind of unusable data. No carmaker publishes a text for U04BB. U01B8 stands for total silence of module B. Expect individual buttons, often a group in one console or panel, to stop responding.

Likely causes

Replacement switch module of the wrong variant or not coded to the vehicle
Switch input module B internally faulty
Loose or corroded plug between satellite and main module

Symptoms

  • A group of buttons in one panel not responding
  • Functions switching on by themselves or not switching off

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–350
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

switch input module b

Related codes

U01B8U04BAU04BC

References: patents.google.com, patents.google.com.