U0136

Universal

Lost Communication With Differential Control ModuleRear

Definition source: General OBD-II reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
Medium Severity

The vehicle has detected that messages from the rear differential control module are not being received over the vehicle’s communication network. That module coordinates rear differential functions when equipped, but its exact role varies by vehicle. The code identifies a communication problem, not proof that the module itself has failed.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the vehicle has unusual handling, unexpected drivetrain behavior, or a warning that affects safe operation, stop somewhere safe and arrange an inspection. If it drives normally, avoid demanding driving until the issue is diagnosed, especially if drivetrain warnings are present.

Common Symptoms

  • There may be no noticeable symptoms if the communication loss is intermittent or the controlled functions are not currently needed.
  • A drivetrain, differential, or related warning light may appear because another module has detected missing messages.
  • Some rear differential functions may be unavailable or limited, depending on the vehicle’s design.
  • Other communication-related codes may appear if the problem affects additional modules or the shared network.

Common Causes

  • Low or unstable vehicle battery voltage can interrupt module operation or network communication.
  • A blown fuse or a problem in the module’s power or ground circuit can prevent it from communicating.
  • Damaged wiring, corrosion, moisture, or a loose connection in the module’s connectors or network wiring can interrupt messages.
  • A fault elsewhere on the vehicle communication network may prevent messages from reaching or leaving the module.
  • The rear differential control module may have an internal fault, but this should be considered only after its circuits and network connections are checked.

Diagnostic Steps

  1. Note any warning lights, changes in vehicle behavior, and when the issue occurs; this helps a technician relate the code to the symptoms.
  2. If you have a suitable scan tool, record the codes from all modules before clearing anything. Related codes can help distinguish a module-specific issue from a wider network or voltage problem.
  3. With the vehicle safely parked and switched off, check the battery terminals for obvious looseness or corrosion. Do not disconnect modules or wiring as a diagnostic shortcut.
  4. Visually inspect accessible wiring and connectors related to the rear differential control system for obvious damage, moisture, or looseness. Avoid reaching near moving parts or working under an unsupported vehicle.
  5. If the code returns or drivetrain behavior is abnormal, have a qualified technician check the module’s power, ground, connectors, and network communication using vehicle-specific information.

When to Call a Professional

A technician can scan all modules to confirm which ones report the communication loss and check whether the rear differential module responds. Diagnosis may include inspecting relevant fuses, power and ground circuits, connectors, wiring, and the vehicle network using the model-specific wiring information and test procedures. The code alone does not justify replacing the module.

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Commonly Asked Questions

Does U0136 mean the rear differential control module is bad?

No. It means communication with that module was lost. Power, ground, wiring, connectors, network faults, or the module itself can cause the condition, so testing is needed before replacing parts.

Can I keep driving with U0136?

It depends on whether the vehicle has symptoms and which rear differential functions are affected. If handling or drivetrain behavior is unusual, or a warning indicates unsafe operation, stop and arrange an inspection. If there are no symptoms, have the fault checked promptly and avoid demanding driving until its effects are understood.

Why are there other communication codes as well?

Several modules may report missing messages when a shared network, power supply, or ground is affected. Scanning all modules helps show whether the issue is limited to the rear differential control module or is broader.

Will clearing the code fix the problem?

Clearing a code does not repair the cause. Record all codes first; if the communication problem remains, the code may return.

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