U0110
Lost Communication with Drive Motor Control Module "A"
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Code U0110 indicates that the vehicle's hybrid control system has lost communication with Drive Motor Control Module 'A'. This module—often integrated into the inverter assembly—controls the main electric drive motor in hybrid and electric vehicles. It converts DC power from the high-voltage battery into AC power for the motor and manages regenerative braking. When communication is lost, the electric drive system is effectively disabled.
On most hybrid vehicles, the car can still limp along using only the gasoline engine, but you will lose electric motor assist, regenerative braking, and hybrid fuel economy benefits. Some hybrid designs may not be able to operate at all without the drive motor controller, as the electric motor may be required for starting the gasoline engine (vehicles without a traditional starter motor). In these cases, the vehicle will not start.
This is not a DIY-friendly repair due to the high-voltage systems involved. Hybrid vehicle high-voltage systems operate at 200-600 volts and can be lethal if handled improperly. However, before visiting a specialist, check the simple things: the 12V auxiliary battery is a common culprit and is safe to inspect and replace yourself. If the 12V battery tests good, the vehicle should be taken to a hybrid-certified technician who can safely diagnose the high-voltage system, inverter, and associated wiring.
Severity
Symptoms
- •Hybrid system warning light or Check Hybrid System message displayed
- •Loss of electric motor assist, vehicle runs on gasoline engine only
- •Reduced fuel economy due to loss of hybrid functionality
- •Vehicle enters limp mode with significantly reduced power
- •Regenerative braking may not function, affecting brake feel
- •Vehicle may not start if the hybrid system cannot initialize
Likely Causes
The Drive Motor Control Module connects to both the high-voltage hybrid battery and the CAN bus. Wiring damage from road debris, corrosion, or improper service work can sever the communication link while potentially leaving the motor physically intact.
The inverter/motor controller converts DC battery power to AC for the drive motor and contains complex power electronics. Component failures in the inverter—particularly IGBTs or capacitors—can cause the module to crash and stop communicating.
Even though hybrid vehicles have a high-voltage traction battery, the control modules still run on the 12V auxiliary battery. A weak 12V battery can cause the drive motor controller to lose its CAN bus connection.
If the high-voltage battery contactors fail to close or the battery management system detects a fault, it may shut down the drive motor controller as a safety precaution, causing it to drop off the CAN bus.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Check the 12V auxiliary battery voltage and replace if weak or failing
- Inspect CAN bus connectors at the drive motor controller for corrosion or damage
- Verify all high-voltage safety interlocks are properly engaged
- Clear the code and test drive—may be caused by a temporary communication glitch
- Have the inverter/motor controller diagnosed by a hybrid-certified technician