Lost Communication With Traction Motor Control Module B
What does U0145 mean?
The U0145 code means the vehicle's onboard diagnostic system has detected: Lost Communication With Traction Motor Control Module B. This is a critical severity code.
Common Symptoms
- Electric drive system malfunction warning
- Rear or secondary electric motor inoperative
- AWD function lost on electric/hybrid AWD vehicles
- Reduced power warning displayed
- Vehicle may limp or not move
Probable Causes (Ranked by Likelihood)
- Failed secondary traction motor controller Very High
- Damaged CAN bus wiring to motor module B High
- Secondary inverter overheating Moderate
- High voltage connector loose or damaged Moderate
- Coolant leak in rear motor assembly Low
Step-by-Step Diagnostic Procedure
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Scan all hybrid/EV powertrain modules for DTCs
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Check CAN bus wiring between primary and secondary motor controllers
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Verify 12V system voltage is adequate
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Inspect high-voltage connectors at the secondary motor assembly
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Check cooling system for the rear motor -- look for coolant leaks
Frequently Asked Questions
Can I drive with code U0145?
No. The secondary traction motor controller has lost communication. On AWD electric vehicles, this disables the rear or front motor. The vehicle should be towed to an EV-qualified repair facility.
What is traction motor module B?
In vehicles with dual electric motors (like AWD EVs), module B controls the secondary motor. This is typically the rear motor in electric AWD systems.
Is U0145 expensive to fix?
Secondary motor controller repairs can cost $400 to $3500 depending on the vehicle and whether the controller or the motor itself needs replacement.