2021 Thomas Built Buses Minotour

The Office of Defects Investigation (ODI) opened this Preliminary Evaluation (PE) after receiving one Vehicle Owner Questionnaire (VOQ) complaint related to four school buses built on General Motors (GM) van chassis. The VOQ alleged transmission failure resulting in a loss of all forward gear. In ODI's pre-investigative discussions with GM, ODI learned that valve body separator plates had been machined out of tolerance during production periods between October 2016 to April 2017 and February 2021 to April 2021. This out of tolerance machining may create excessive wear to the valve body check balls, possibly resulting in an inability to engage drive or reverse. The potential loss of drivability only begins when shifting from a park or neutral transmission selection and does not occur during a functional drive cycle. The average failure mileage of vehicles which experienced this condition is within warranty and related claims or complaints did not include any accidents, injuries, or fatalities. After discussions with GM, Technical Service Bulletin (TSB) 23-NA-142 (NHTSA ID number 10243753) was released in September 2023. This technical service bulletin provides a procedure for technicians to replace the forward check ball and separator plate if found to be the cause of a customer's concern. During the course of the investigation, GM also released a Customer Satisfaction Program (CSP) N232428780 (NHTSA ID 10253316) in February 2024, to notify school bus and ambulance fleets of the concern and to proactively mitigate the risk in these essential-operation vehicles. Recently, ODI contacted multiple school bus fleets, verifying that there have not been any stranded buses mid-route from this condition. Additionally, ODI has not received any additional VOQ complaints since the opening of this investigation. Based on the available information, including GM's TSB and CSP, this PE is closed. The closing of this investigation does not constitute a finding by NHTSA that a safety-related defect does not exist. The Agency reserves the right to take additional action if warranted by future circumstances. To review the ODI report cited in the Closing Resume ODI Report Identification Numbers document, go to NHTSA.gov.

Important Campaign Information Letter for Dealer Travel for Campaign Performance – TBB.

Revised Warranty Information Letter for OWL and Warranty Manual Improvement: Sublets and Travel Time/Distance. In the spirit of continuous improvement, DTNA reviewed sublet-related policies and procedures. The goal was to improve language clarity and optimize processes. Revisions are in blue font.

Customer Advisory Letter for a software update is needed to address a possible water condensation build up in the air compressor. The EV Control Unit (ECU) software and air dryer will be updated on your vehicle.

Tech Talk discussion about power steering fluid.

Service Solution for TBB buzzer sounds when either driver's door or the entrance door is open. This Service Solution is provided to assist Dealers/Customers in resolving the buzzer sounding when either the driver's door or entrance door is open. With certain options, a diode was inadvertently being removed.

Warranty Information Letter for OWL and Warranty Manual Improvement: Sublets and Travel Time/Distance. In the spirit of continuous improvement, DTNA reviewed sublet-related policies and procedures. The goal was to improve language clarity and optimize processes.