Data Link Communication Failure
Indicates a failure in communication over the data link between devices.
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What it means (plain English)
The vehicle’s computer is trying to talk to another part of the system but isn't getting a response back, which can happen due to wiring issues or a faulty component.
What the computer is actually seeing
The Electronic Control Unit (ECU) expects a certain response from another module (like the Engine Control Module, or ECM), typically sending a request signal and waiting for a return signal within milliseconds. If it doesn't receive the expected signal, it registers a fault.
What a healthy reading looks like
Signal expected from the communicating module within 10 milliseconds; voltage levels should be around 2.0 to 2.5 volts for low signal and 4.5 to 5.0 volts for high signal during communication.
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. Check the vehicle's battery voltage, should be above 12.5 volts. If below, charge or replace the battery.
- 22. Inspect all data link connectors for corrosion or loose connections. Repair as necessary and retest.
- 33. Verify the integrity of wiring between the ECM and the affected module by checking for continuity and short circuits. Replace damaged wiring if found.
- 44. Scan for other active codes that might indicate a related module issue. Address those codes first before moving ahead with repairs.
- 55. If no wiring issues are found, replace the suspected faulty component (ECM or the module communicating with it) and recheck for the code.
Common causes
- Bad wiring or connectors between modules
- Faulty ECM or related module
- Incorrectly configured communication protocols
- Low battery voltage or poor electrical connections
Typical repair cost
$$$ - $$$$
Related codes
Frequently asked questions
Is it safe to continue driving the vehicle with this code?
It's moderate severity; you may experience drivability issues but it shouldn't cause immediate safety concerns.
Will this issue come back after I fix it?
If the root cause is not addressed, like bad wiring, it may return.
Why does this code appear with other codes?
These codes often indicate related communication failures; one module’s failure can cascade and affect others.
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