Volvo Trucks North America is recalling certain 23,000 2007-2014 VAH, VHD, VNL, VNM, and VT models because of an omission that could lengthen stopping distances. The affected vehicles were manufactured from December 20, 2006 through May 22, 2013.

A National Highway Traffic Safety Administration bulletin says the affected vehicles were built without a redundant clutch disengagement switch.

Without a redundant switch, a loss of signal from the brake air pressure switch can prevent the clutch from automatically disengaging when the brake is applied. Without a signal to disengage the clutch when the brakes are applied, the distance required to stop the truck may lengthen, increasing the risk of a crash.

NHTSA’s Office of Defects Investigation says it is aware of 134 of these vehicles with one or more complaints or field reports related to this condition and is aware of 164 with one or more warranty claims related to this condition.

All suspect trucks were originally equipped with automated manual transmissions. According to Volvo, reports of the subject transmission clutch mechanism failing to automatically disengage as intended are associated with the removal of a brake pedal micro switch that provided a redundant signal to the transmission control module indicating the brakes had been applied. Previously, Volvo had removed this brake pedal micro switch from new vehicle production and from certain vehicles already in-service via two field service campaigns because it decided the switch was unnecessary and/or a maintenance issue.

in the absence of this redundant brake pedal micro switch, the clutch mechanism may fail to disengage the transmission from the engine at low vehicle speed should the stop lamp switch fail to send and/or the transmission control module fail to receive the primary signal.

The remedy for this recall campaign is still under development but is expected to begin by August 25.

Volvo's recall number is RVXX1303. Owners may contact Volvo at 1-336-393-2000. Owners may also contact the National Highway Traffic Safety Administration Vehicle Safety Hotline at 1-888-327-4236.