DETROIT (AP) – Under pressure from the federal government, General Motors is recalling more than 3.4 million pickups and SUVs in the US to fix a braking problem.
The recall concerns the Chevrolet Silverado and GMC Sierra 1500, 2500 and 3500 model year 2014-2018 pickups. Also included are the 2015-2017 Cadillac Escalade and the 2015 GMC Yukon and Chevy Suburban and Tahoe.  GM states that the pump in the power brakes can generate less negative pressure as it ages
The recall comes after the National Highway Traffic Safety Administration began investigating the problem in November last year.
Dealers will recalibrate the electronic brake control module for free to customers. Owners should be notified from 6th September.
NHTSA, the government's road safety department, began investigating the problem last year after 1
GM says the problems rarely and mostly occur at low speeds such as driving in parking lots. Despite the problem, "the brakes continue to function and exceed the requirements of the corresponding nationwide safety standard for motor vehicles," said GM spokesman Dan Flores.
The vacuum pump is lubricated with engine oil that flows through a filter screen. In some trucks, oil sludge or other debris can clog the screen, reduce oil flow, and cause the pump's vacuum to drop, Flores said.
The trucks have a secondary brake assist system that works when there are problems with the main system, but it is limited at lower speeds. Reprogramming activates the secondary system faster.
GM does not replace the pumps because pump outages are rare and already covered by an extended warranty, Flores said. "This remedy will improve braking performance in any situation where the brake vacuum drops," he said.
The recall comes 10 months after NHTSA initiates its investigation. When asked why the recall had taken so long, Flores just stated that the company had worked with NHTSA and provided data.
Drivers may feel a vibration in the brake pedal or a pressure change required to depress the brake pedal if their trucks have the problem with the vacuum pump. When the problem occurs, owners are prompted to wait for the brake assist system in a message on their dashboard, Flores said.
Although the recall is a large number, the cost will not be high enough to be reported by GM to the Securities and Exchange Commission as this will have a material impact on the outcome, Flores said. He said he did not know the cost.