2023 Hyundai Ioniq 5 Lighting Problems

When using the one pedal driving or "iPedal" mode, the brake lights do not illuminate when braking unless your foot is completely off of the accelerator pedal. This is very dangerous because the vehicle can be stopped very hard without completely removing your foot from the gas pedal. I have stopped using this mode after almost being rear-ended three times within a week due to the car behind me not realizing that I am braking. This issue is gaining media attention. After doing research online, I have learned that there are lots of other people that have noticed the same behavior and have stopped using this mode as a result.

The Ioniq 5 when using level 2 regen, level 3 regen, and i-pedal (one pedal driving), does not turn on the break light when decelerating, even if coming to a full stop unless the driver removes their foot completely from the pedal or hits the break pedal. These driving modes allow the driver to perform regenerative breaking almost to a complete stop without turning on the break lights and warning other drivers behind you. With i-pedal specifically, the driver can 100% perform all stop and go traffic maneuvers without using the break and never have the break lights activate. This appears to be the default behavior of all Ioniq 5 vehicles and is controlled via software. The vehicle does not appear to measure rate of deceleration so even if the driver were to decelerate rapidly, the brakes would not activate. This has been extensively demonstrated on youtube and the best video example of this problem can be found here: https://www.youtube.com/watch?v=U0YW7x9U5TQ

When my car is configured to one pedal driving mode (iPedal), the brake lights only illuminate when the accelerator pedal is fully released. This means the car may decelerate rapidly (up to 0.25G or 2.5m/s^2 according to a report) under regenerative braking, while the brake lights remain off. I believe this is a safety hazard that can increase the chances of rear-end accidents.

The Ioniq 5 offers a multi-level regenerative braking system, which slows the car down to varying degrees when letting off the accelerator pedal. While these systems work well to increase efficiency, the behaviour of the brake lights while in use is concerning. Very often the car is slowing considerably, enough to be akin to light braking, but the brake lights do not activate. This can be full let off the accelerator pedal and slowing with not brakes, or with a partial lift (especially on higher regen levels), where the vehicle is obviously slowing but the brake lights do not activate. This has been talked about on various forums and some review videos, and I expect this is not the first complaint placed about this issue. So far it has not caused a problem with my vehicle, but I have had to alter my driving habits to account for this, and it at times renders some of the vehicles technology dangerous to use, despite that technology being added to the car as a benefit to the driver under most conditions.

While driving in the one pedal driving mode (“iPedal”), it is possible to rapidly slow the vehicle while keeping the accelerator pedal slightly depressed, which is the expected result for this regenerative braking mode. While rapidly decelerating in this mode, however, the brake lights do not illuminate while the accelerator pedal is slightly depressed. Even though regenerative braking is active and the car is rapidly decelerating, there is no brake light illumination. The brake lights only turn on if the accelerator pedal is not pressed at all, which during typical one-pedal driving only occurs at the very end when coming to a complete stop, or when stopping suddenly during a cut-in or at a light. This is a serious safety concern because the vehicle will decelerate very quickly with no visual warning lights to other drivers behind the vehicle. I have noticed that this issue has been reported by other drivers online, but I have not yet taken the vehicle to be inspected by the dealer. There is no indication of failure on the dashboard.