Network, generic

U0274 Lost Communication With Lighting Driver Control Module B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0274 is stored when the second lighting driver control module stops answering on its network. Lincoln documents a B unit on the 2025 Navigator, listed as LDCMB and updated with the same release 25.10.08 as its three siblings, but gives no position for it. What a silent driver does on its own is shown by TI's TPS92520-Q1 LED driver: a communication watchdog, set to about 1.67 s by default, switches the chip to limp-home current from preset registers when commands stop arriving. The lamp therefore often stays lit at a fixed level although the controller has lost the module. No manufacturer documents U0274 publicly. U0575 covers implausible data from the same unit.

Likely causes

Bus wire or connector to driver module B open or corroded
Supply or ground of driver module B missing
Driver module B software not current after an update
Driver module B internally faulty

Symptoms

  • Lamp stays at one fixed brightness and ignores dimming
  • Lighting fault message
  • Adaptive light functions switched off

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–1,200
Time0.3–3 h

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

Parts involved

lighting driver module bvehicle bus wiring

Related codes

U0575U0273U0275

References: static.nhtsa.gov, ti.com.