Lost Communication With TCM
What does U0101 mean?
The U0101 code means the vehicle's onboard diagnostic system has detected: Lost Communication With TCM. This is a critical severity code.
Common Symptoms
- Check Engine Light illuminated
- Transmission stuck in limp mode
- No shifting -- stuck in one gear
- Transmission warning light on
Probable Causes (Ranked by Likelihood)
- TCM power supply or ground failure Very High
- CAN bus wiring fault to TCM High
- Failed TCM Moderate
- Corroded TCM connector Moderate
Step-by-Step Diagnostic Procedure
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Check TCM power and ground circuits
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Inspect TCM connector for corrosion or water intrusion
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Check CAN bus wiring between TCM and gateway module
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Verify TCM communicates using a scan tool
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Replace TCM if power, ground, and CAN bus are confirmed good
Frequently Asked Questions
Can I drive with code U0101?
Drive short distances only. Lost communication codes indicate a module has stopped communicating on the vehicle network. The affected system may not function correctly.
What causes U0101?
The most common cause is a failed module or a wiring issue in the CAN bus network. TCM power supply or ground failure is the most likely cause. Power supply, ground, and connector issues should be checked before replacing any module.
Is U0101 expensive to fix?
Repair costs range from $100 - $1200 (parts and labor). Wiring repairs are on the lower end, while module replacement is on the higher end. The module may also need to be programmed after replacement.