What it means
Fault on the combined ACC/OFF ignition input. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
The combined accessory/off ignition input tells a control module whether the ignition switch is in the accessory or off state. The module monitors that input and sets U3022 when the ACC/OFF signal is faulty or inconsistent with the expected state. Incorrect state information can interfere with module wake-up, shutdown, or communication.
Common causes
Most likely first.
- Ignition switch contacts worn
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Save freeze-frame data and scan all modules for ignition-state and communication faults to see whether the issue occurs in ACC, OFF, or during a transition.
- Compare the module's reported ACC/OFF state in live data with the actual key or switch position.
- Inspect the ignition switch connector and related wiring for loose terminals, wear, corrosion, or damage.
- Check the ACC/OFF input circuit and switch operation through each ignition position, using the manufacturer's wiring diagram and specification.
- If the switch and circuit test correctly, check gateway handling and CAN network termination against the manufacturer's specification.
Common fixes
- Repair loose or damaged wiring in the ACC/OFF input circuit.
- Clean or repair corroded ignition switch connectors.
- Replace a worn ignition switch if testing confirms its contacts do not provide the correct ACC/OFF states.
- Correct a confirmed gateway routing or CAN network termination fault if the ignition input is sound.
Can I keep driving?
A faulty ACC/OFF input can cause modules or accessories to stay on, shut down unexpectedly, or fail to communicate. If warning lights or vehicle functions are affected while driving, stop somewhere safe and have the fault assessed.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.