Lost Communication with Rear Seat Control Module
The main computer can't talk to the rear seat control module.
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 main computer in the vehicle is trying to send messages to the rear seat control module, like commands for seat adjustments or entertainment controls, but it's not getting a response back. This could mean a broken wire, a bad connector, or the control module itself is faulty.
What the computer is actually seeing
The main computer (ECM/BCM) expects to receive normal communication signals from the rear seat control module continuously in short intervals (typically around 100-200 milliseconds). If it doesn't see these signals for a certain period, it will flag this code.
What a healthy reading looks like
Module communication is expected every 100-200 milliseconds; no data received leads to a DTC within 5 consecutive missed cycles.
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 the wiring and connectors between the rear seat control module and the BCM for any visible damage or corrosion. Decision: If there's damage, repair it. If not, proceed to step 2.
- 22. Check for any other codes present that may indicate a broader communication issue (U0100, U0101, etc.). Decision: If yes, diagnose those codes first. If no, proceed to step 3.
- 33. Test the rear seat control module's power and ground circuits. Expected voltage should be around 12 volts. Decision: If voltage is correct, replace the rear seat control module. If voltage is incorrect, check power/ground wiring.
- 44. Verify that all modules are updated with the latest software. Decision: If updates are available, apply them and recheck the code. If not, proceed to final step.
- 55. If all tests pass but the code persists, replace the body control module.
Common causes
- Corroded or damaged wiring harness to the rear seat control module
- Faulty rear seat control module
- Disconnection at the connector
- Faulty body control module (BCM)
- Software glitch in the control module
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but rear seat functions will be affected. You should address it soon.
Will this code come back after repair?
If the underlying issue is fixed, it shouldn't return. If related wiring or components are neglected, it may come back.
Why do I see this code with U0100?
Both codes relate to communication failures, so they can occur together if there's a network issue.
Working a real vehicle right now?
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