U0136 Code – Lost Communication With Rear Differential Control Module

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Fault Code Description

The U0136 Diagnostic Trouble Code (DTC) indicates that one or more control modules have lost communication with the Rear Differential Control Module over the Controller Area Network (CAN) bus. This module manages the operation of the rear differential in AWD and 4WD vehicles, helping optimize traction and torque distribution. When communication is interrupted, the drivetrain may enter a fail-safe mode and store the U0136 code.

Symptoms

  • Check Engine Light or AWD/4WD warning light illuminated.
  • Rear differential system warning message.
  • AWD or 4WD system becomes unavailable.
  • Reduced traction and vehicle stability.
  • Additional CAN communication DTCs may be stored.

Common Causes

  • Open or short circuit in CAN High or CAN Low wiring.
  • Blown fuse supplying the Rear Differential Control Module.
  • Poor battery voltage, power supply, or ground connection.
  • Loose, damaged, or corroded electrical connectors.
  • Faulty Rear Differential Control Module.
  • Incorrect module programming after replacement.

Severity

Severity: Moderate to High. The vehicle may still be driven, but rear differential control and AWD/4WD performance may be reduced or disabled, resulting in decreased traction and handling on slippery or off-road surfaces.

Average Repair Cost

  • CAN bus wiring repair: $100–$350
  • Power or ground circuit repair: $80–$250
  • Connector cleaning or replacement: $50–$200
  • Fuse replacement: $10–$50
  • Module programming: $100–$300
  • Rear Differential Control Module replacement: $400–$1,300+

Diagnosis

  1. Scan all control modules for stored DTCs.
  2. Inspect related fuses and verify battery voltage.
  3. Check power and ground circuits.
  4. Inspect CAN High and CAN Low wiring for opens or shorts.
  5. Examine connectors for corrosion or loose terminals.
  6. Verify communication with the Rear Differential Control Module using a professional scan tool.
  7. Reprogram or replace the module if communication cannot be restored.

Common Repairs

  • Repair damaged CAN bus wiring.
  • Replace blown fuses.
  • Repair power or ground circuits.
  • Clean or replace damaged electrical connectors.
  • Reprogram the Rear Differential Control Module.
  • Replace the Rear Differential Control Module if confirmed faulty.

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