The cost of this repair ranges from $5,000 to $15,000 for semi truck transmissions, so it’s not something you want to take a chance on. If you’re out driving and your transmission fails without warning, it’s best not to keep driving or try going down the road at slower speeds as this could cause more damage and costly repairs. Instead, pull over as soon as possible and contact your nearest qualified truck transmission repair center or tow service for immediate help. The goal is to get the vehicle out of traffic ASAP. It may also be prudent to warn other drivers of the danger in the vicinity by putting on hazard lights and positioning safety cones nearby.