U029C Lost Communication with Drive Motor Control Module D
The U029C code indicates that the vehicle's ECM/PCM has lost communication with the Drive Motor Control Module D. This module manages one of the electric drive motors in hybrid, electric, or multi-motor propulsion systems. The 'D' designation suggests the vehicle has multiple drive motor control modules (A, B, C, D, etc.), typically found in all-wheel-drive or complex powertrain configurations. Loss of communication can result from CAN bus faults, electrical interruptions, or module failure.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Faulty wiring or connectors in the CAN bus between the ECM and Drive Motor Control Module D
- Internal failure of the Drive Motor Control Module D
- Power or ground supply issue to Module D
- Faulty network bus terminator or electromagnetic interference
- Corrosion or physical damage to harness connectors
3. Symptoms You Will Notice
- Check Engine Light or hybrid system warning light illuminated
- Reduced vehicle performance or loss of electric drive power
4. Step-by-Step Diagnosis
Scan for additional related codes and check freeze frame data
Inspect CAN bus wiring and connectors for damage, corrosion, or loose connections
Verify power and ground at the Drive Motor Control Module D connector
Check CAN bus resistance and signal integrity with an oscilloscope
If wiring and power are OK, suspect a failed module and perform module replacement after programming
5. Frequently Asked Questions
Is it safe to drive?▼
No, this is a high-severity fault. Driving may cause loss of drive power or unsafe operation. Have the vehicle towed to a repair facility.
How much does it cost to fix?▼
Diagnosis typically costs $100-$200. Repair costs vary widely: wiring repairs $150-$400, module replacement $800-$2,000 including parts and labor.