Lost Communication with Body Control Module
The engine control module can't communicate with the body control module.
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What it means (plain English)
The car's engine control computer is unable to talk to the body control module, which controls things like lights and windows. This usually means there's a wiring problem or the body control module itself has failed.
What the computer is actually seeing
The engine control module (ECM) is expecting to receive signal information from the body control module (BCM) at regular intervals, usually every 10-50 milliseconds, but it hasn't received it over a set time frame, typically around 2 seconds after startup.
What a healthy reading looks like
The ECM expects to see a CAN (Controller Area Network) message from the BCM within the communication protocol. If no data is received in a 2 second window, this code triggers.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect wiring and connectors between the ECM and BCM for damage or corrosion. Repair as needed.
- 22. Check the battery voltage, which should be 12.5V or more. Ensure battery connections are tight.
- 33. Verify that the fuse for the body control module is intact and not blown, replace if necessary.
- 44. Use a scan tool to communicate with the BCM directly. If you cannot connect, the module may be faulty or require a reflash.
- 55. If everything appears functional, replace the BCM if it’s non-communicative after verifying connections.
Common causes
- Damaged wiring between ECM and BCM
- Corroded or loose connectors
- Faulty body control module
- Power supply issues to BCM from fuses or relays
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with U0146?
Yes, but features controlled by the body control module may not work properly.
Will U0146 come back after fixing it?
If the underlying issue is resolved, the code should not return.
Why does it pair with U0131?
U0131 also indicates a communication issue with another module, often related to similar wiring problems.
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