CAN Communication - Control Module Communication Fault
There's a problem with communication between control modules on the CAN bus.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The truck's computer isn't getting messages from one control module to another, which can stop parts from working properly.
What the computer is actually seeing
The engine control module (ECM) isn't receiving the usual messages from another control module (like ABS or transmission), causing a fault code to trigger.
What a healthy reading looks like
Expected message signals are typically between 1.5 to 2.5 volts on the CAN bus lines when active. If voltages drop below 1 volt, communication errors likely occur.
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 wiring and connectors at the control module in question for any visible damage or corrosion. If present, repair or replace. Decision: Is the wiring good? If yes, go to step 2. If no, fix wiring and retest.
- 22. Inspect the integrity of the CAN bus throughout the vehicle for continuity and shorts. Use a multimeter to check voltage on the CAN High and CAN Low lines. Decision: Are voltages normal? If yes, go to step 3. If no, repair the bus lines and retest.
- 33. Swap the suspected faulty control module with a known good module and check if the fault code clears. Decision: Does the code clear? If yes, replace the faulty module. If no, there may be a deeper issue in the wiring or other modules.
Common causes
- Poor wiring connections or damaged harness
- Faulty control module
- Intermittent communication issues from harness chafing or grounding points
- Defective CAN bus termination resistors
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
While it may still drive, limited functionality of parts could become a safety issue, so it's best to address it soon.
Will this code come back after clearing it?
If the underlying issue isn't fixed, the code will likely return after clearing.
What systems could this affect?
It could impact any system relying on communication between modules, like brakes, transmission, or engine performance.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
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