Network, generic

U029C Lost Communication With Drive Motor Control Module D

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Letter D refers to the controller of a fourth drive motor, which presupposes individual-wheel drive. Rivian's quad-motor R1S is the familiar production case: each wheel gets its own frame-mounted Bosch motor, so torque can be split freely between all four corners at any time. U029C says module D has gone silent on the network. If it still sent frames with bad content, U059D would be stored instead; a silent third motor is U029B. No manufacturer documents U029C publicly, so which wheel letter D belongs to and how the car reacts are vehicle-specific. CARB 1968.2 obliges hybrid OBD systems to notice when a digital input stops communicating. A plausible response is to drop the silent motor, cap the torque on the other side so the car still runs straight, and warn of reduced power.

Likely causes

Fuse, low-voltage supply or ground of module D faulty
Bus wiring near the wheel drive unit chafed or wet
Software fault or failed update of module D
Drive motor control module D internally failed

Symptoms

  • Reduced power and loss of torque vectoring
  • Drive system warning in the cluster
  • Uneven traction when accelerating

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–6,000
Time1–6 h

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

Parts involved

drive motor control module dvehicle bus wiring

Related codes

U029BU0292U059D

References: law.cornell.edu, en.wikipedia.org, en.wikipedia.org.