What should you avoid doing on wet or icy roads regarding retarders?

On wet or icy roads, it is crucial to avoid engaging retarders, like engine brakes, as they can lead to loss of traction. This is particularly important because, when used improperly under slick conditions, they can cause the vehicle to skid or lose control.

Turning off the retarder is the most appropriate action since it prevents sudden deceleration that could destabilize the vehicle on slippery surfaces. The use of retarders becomes problematic on wet or icy roads because they can cause the drive wheels to lock up, especially if they are activated aggressively or inappropriately.

In contrast to turning them off, using them aggressively can further worsen traction issues, while continually keeping them engaged can lead to dangerous scenarios. Testing their effectiveness can also introduce unnecessary risk, as it requires the driver to experiment with braking performance under potentially hazardous conditions. Therefore, turning off the retarder is the most prudent course of action to maintain vehicle control in wet or icy conditions.