Aspects of the disclosure relate to stopping a vehicle. For instance, a vehicle is controlled in an autonomous driving mode by generating first commands for acceleration control and sending the first commands to an acceleration and/or steering actuator of an acceleration system of the vehicle in order to cause the vehicle to accelerate. Acceleration and/or orientation of the vehicle is monitored while the vehicle is being operated in an autonomous driving mode. The monitored acceleration and/or orientation is compared with the first commands. An error with the acceleration and/or steering system is determined based on the comparison. When the error is determined, the vehicle is controlled in the autonomous driving mode by generating second commands which do not require any acceleration and/or steering.