{"nhtsa_id":10163635,"type":"service_bulletin","type_name":"Service bulletin","date_added":"2019-08-12","date":"2019-07-10","document_id":"19-TR-19EN","mfr_campaign":null,"replaces":null,"component":"ELECTRICAL SYSTEM:SOFTWARE","mfr_system":null,"summary":"Service tip for the optional Preselect Optimization feature. The transmission will not initiate preselect downshifts when the engine brake is active, unless the service brake is simultaneously depressed. Correction: If closed throttle Engine Brake Preselect downshifts without depressing service brake are desired, then the ENGINE BRAKE: Automatic Preselect Optimization (CMC) setting must be changed to NONE using the reprogramming function in Allison DOC® (see Figure 1). The TCM will revert to the defined Engine Brake Interface, Input H / Output A or Input I / Output A parameters. The Engine Brake Automatic Preselect Optimization logic will be disabled. Grade Braking Automatic Preselect Optimization and Cruise Control Preselect Optimization will be unaffected","document":{"url":"https://static.nhtsa.gov/odi/tsbs/2019/MC-10163635-0001.pdf","alternate_url":"https://static.nhtsa.gov/odi/tsbs/2019/MC-10163635-9999.pdf","confirmed":false},"url":"https://open.wenmarpro.com/bulletins/10163635","components":[{"id":"electrical","name":"Electrical system","parent":null},{"id":"software","name":"Software","parent":"electrical"}],"codes":[],"topics":[],"vehicles":[{"make":"ALLISON","model":"TRANSMISSION","year_from":null,"year_to":null,"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":[]}