What it means
A control module has stopped receiving expected messages from the rear differential control module. Rear differential functions managed by that module may be limited or unavailable.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
The rear differential control module exchanges network messages used to manage rear differential functions. U0136 sets when another module stops receiving expected messages from that rear module, which can make its controlled functions unavailable.
Common causes
Most likely first.
- Rear differential control module power or ground fault
- Damaged network wiring or connector
- Rear differential control module failure
- Low system voltage
Symptoms
- Drivetrain or chassis warning
- Rear differential functions may be unavailable
- Other communication codes
How to diagnose it
- Scan all modules and check freeze-frame data for U0136 alongside low-voltage or other communication codes.
- Check battery condition and charging-system operation because low voltage can disrupt communication with the rear differential module.
- Inspect the rear differential module connector and exposed harness for looseness, corrosion, water, or impact damage.
- Check the module's power and ground circuits under load against the manufacturer's specification using the correct wiring diagram.
- Test the network wiring to the rear differential module for opens, shorts, or poor connections according to the manufacturer's procedure.
- If its power, ground, and network connections are sound, check for a scan-tool response before condemning the rear differential module.
Common fixes
- Restore battery or charging-system performance if voltage is low.
- Clean, secure, or repair a damaged rear differential module connector.
- Repair damaged network wiring to the rear differential module.
- Repair the module's power or ground supply.
- Replace and configure the rear differential control module if it does not communicate with sound circuits.
Can I keep driving?
Avoid towing, aggressive acceleration, or slippery terrain if the rear differential warning is on or its functions are unavailable. The vehicle may have reduced rear differential control, and handling or traction can be affected.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.