OBD data: overview
The 2nd-generation Aion V reports a lot about itself through the normal OBD port under the dashboard: battery charge and health, every cell voltage, temperatures, energy used, wheel speeds, gear, doors, locks, windows, tyres and more. GAC doesn't publish what those values mean, so we worked them out ourselves on a 2026 Sri Lankan right-hand-drive car with a small home-made logger. Everything is shared here so nobody has to repeat the work.
So far: 71 items with a known meaning, 63 good guesses and 410 still unknown, from 15 of the car's 22 diagnostic modules, after trying over 95,000 item numbers. The full list, searchable, is on the item list.
| Battery | Charge (as on the dashboard), health, pack voltage, all 112 cell voltages with the highest, lowest and average, 24 battery temperatures, energy charged and used over the car's life, charge and discharge power limits. |
|---|---|
| Driving | Speed of each wheel, gear, motor speed and torque, motor and drive-unit temperatures, brake pedal, steering angle, yaw rate, sideways and forward g. Candidates still being checked: battery current, hydraulic brake pressure. |
| Body | Each door and the boot, locked or unlocked, all four windows (closed to fully down) and their motors, both indicators, reversing light, brake lights, and the lock / unlock history. |
| Tyres | Pressure and temperature of each tyre (they update while driving). |
| 12 V system | 12 V supply seen by each module, DC-DC converter output and target voltage. |
| Other | A/C request, the car's clocks, and the maker's server addresses the telematics unit uses. |
The odometer (our own estimate, adding up the distance from the wheel speeds, matched the dashboard within 1 km), remaining range, trip meters, accelerator pedal, outside temperature, wipers, seatbelts, the fridge, and what happens while the car charges with nobody in it (our logger isn't powered then yet). The item list ends with a Help wanted list of items that change but have no meaning yet.
A small ESP32 board reads these items through the OBD port whenever the car is on, keeps a log, and sends it over home Wi-Fi to a small server at home. That server keeps every reading, works out each trip (distance, kWh per 100 km, share of regenerative braking) and passes the useful values to Home Assistant: doors, lock, windows, tyres, battery and more. It was built in a day or two and has seen three trips so far: it gets better with every drive.
The car has two diagnostic sockets under the dashboard. Use only the normal OBD port (connector IP25): it goes through the car's gateway, which passes diagnostic requests and nothing else. You can tell it by its contacts: positions 1, 2, 7, 9, 10 and 15 are empty. The other socket, OBD-TEST (IP68), has all 16 positions filled: it connects straight to the car's internal networks, including brakes and airbags. Never plug a scan tool or logger into OBD-TEST. Wiring: IP25 OBD port pins, IP68 OBD-TEST pins, OBD diagnostic system, gateway.
Reading through the normal OBD port is read-only: it asks the car for values and cannot change anything. It's the same port every workshop scan tool uses, so it shouldn't affect your warranty. The only real risk is a wiring mistake (a short circuit) with DIY hardware, which is why a plug-in Bluetooth adapter is the simplest route. The OBD-TEST port is different: a wrong message there can affect the car, so we don't use it.
No. Everything here is read-only. Through the normal OBD port the gateway only passes diagnostic requests. The messages that actually switch the A/C, the fridge or the locks travel on internal networks behind it, and locking is probably protected by message authentication. OBD-TEST is closer to those networks, but it also carries the brake and airbag networks: one wrong message there can disable safety systems. We don't recommend trying. Even if you accept the risk, finding the right messages would take a lot of trial and error on a car you depend on, and it could affect your warranty.
Every meaning on these pages is our own reading, from watching values during drives, charges and guided tests (do one thing, see what changes). They are marked known, guess or unknown, and they may change as we learn more. This is educational material, shared as it is: use it at your own risk. We take no responsibility for damage, faults or warranty claims.