start by changing the tranny fluid and filter. if that doesnt work, check the input and out put sensors. next try adding lucus tranny fix. from there might need a rebuild... GL
The torque converter and clutch are the point where the engine and the transmission engage.
Could be low in transmission fluid. When the fluid gets up to opperating temperature the fluid expands to make it just enough fluid to make the clutch pack engage properly.
The transmission may not shift or engage in forward or reverse until the car warmed up for a few reasons. Two examples of why the transmission will not engage is low or no fluid levels or a leak.
Does the torque converter lock? It should lock on both 3rd and 4th gear. How are the engine temperature and temp gauge? The 4T60-E requires decent temp information to run normally, othw it goes to "limp mode" and will not engage 4th nor lock. T
The neutral safety switch keeps the starter from engaging when the transmission is in any gear EXCEPT park or neutral. A faulty switch would either allow the starter to engage any time or not allow the starter to engage at any time.
Bad transmission rebuilder
transmission won't engage when you push the button on john deer 155c automatic
To engage or disengage the engine from the transmission.
Does the transmission engage when you shift it into drive?
Yes It Wil If The Vacuum Leak Is In A Hose That Gos To you Transmission
Low fluid level if your lucky.
When climbing a steep incline. The automatic transmission will always try to engage a high gear.