{"nhtsa_id":10201621,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2021-09-28","date":"2021-05-18","document_id":"SU2105","mfr_campaign":null,"replaces":null,"component":"ELECTRICAL SYSTEM","mfr_system":null,"summary":"The intent of Service Update SU2105 is to provide service notification of a running product improvement part change to the relay used for diesel exhaust fluid (DEF) line heaters. The new DEF line heater relay will be \"Diode Suppressed\". The new relay change is being made to improve circuit fault diagnostic capabilties. This change implements two new diode suppressed relay part numbers based on bus model application. The new relays are easily distinguishable by color. They have a yellow high temp tape wrap. Models Affected: Vision (BBCV), All American, and TX4 (T3FE, T3RE), with EPA/CARB certified on highway Cummins® Diesel Engine Features Built After 07/26/2021 Subject: The intent of Service Update SU2105 is to provide service notification of a running product improvement part change to the relay used for diesel exhaust fluid (DEF) line heaters. Information: The new DEF line heater relay will be \"Diode Suppressed\". The new relay change is being made to improve circuit fault diagnostic capabilities. This change implements two (2) new diode suppressed relay part numbers based on Blue Bird bus model application. The new relays are easily distinguishable by color. They have a yellow high temp tape wrap. New Diode Suppressed Relay Type, Part Number, And Application: Diode Suppressed “Micro Relay” 10073451 – All American and TX4 (T3FE, T3RE) with Cummins Diesel Engine Features Built After 07/26/2021 Diode Suppressed “Mini Relay” 10073452 – Vision (BBCV) with Cummins Diesel Engine Features Built After 07/26/2021","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2021/MC-10201621-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2021/MC-10201621-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/10201621","components":[{"id":"electrical","name":"Electrical system","parent":null}],"codes":[],"topics":[],"vehicles":[{"make":"BLUE BIRD","model":"ALL AMERICAN SCHOOL BUS","year_from":2022,"year_to":2022,"match":null,"vehicle_ids":[]},{"make":"BLUE BIRD","model":"ALL AMERICAN TRANSIT BUS","year_from":2022,"year_to":2022,"match":null,"vehicle_ids":[]},{"make":"BLUE BIRD","model":"VISION SCHOOL BUS","year_from":2022,"year_to":2022,"match":null,"vehicle_ids":[]},{"make":"BLUE BIRD","model":"VISION TRANSIT BUS","year_from":2022,"year_to":2022,"match":null,"vehicle_ids":[]}],"as_of":"2026-10-19","note":"A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.","attribution":[]}