| Subject: | Accelerator pedal fails to return |
| Components covered: |
|
| Investigations Summary: | The office of defects investigations (odi) received field reports alleging throttle pedals on 2012 - 2013 model year (my) navistar prostar vehicles fail to return to the idle position after being depressed. The field reports describe the non-returning throttle pedals resulting in high engine speeds when bringing the vehicle to a stop. The elevated engine speeds allegedly prevent the engine brake from activating. Odi contacted complainants who indicated the failure of the accelerator pedal to return to the idle position was a random event and they were unsure of how the vehicle might respond from one stopping event to the next. Some drivers indicated they were able to pull the accelerator pedal back from underneath with their foot and bring the engine speed back to normal. Upon request, navistar described the functionality of the subject vehicle throttle pedal as a solid-state rotary position sensor device, which transfers voltage based on shaft rotation in either direction from a reference angle. Shaft rotation is obtained by the driver stepping on the accelerator pedal or allowing the pedal to return back to closed throttle (CT) position. In the case of this alleged defect the throttle does not return completely to the CT position due to stack up tolerance issues and backlash in the pinion/lever arm gear set. Navistar informed odi they released a redesigned throttle pedal assembly (manufactured by williams controls) starting with my 2013 vehicles and all warranty and complaint vehicles were being retrofitted with the new part. Odi has opened this pe to asses the safety risk associated with alleged partially-returning accelerator pedal on the subject vehicles. |
| Vehicles Affected by this investigation: |
|
Defect investigation of headlight failures/fires
Defect investigation of brake s-cam tube bracket failure
Defect investigation of high pressure oil line rupture