Lincoln Automatics have the latest bluetooth scanner for fault finding; we have been reconditioning units for 30+ years. Since early 2003 a lot of transmissions have computers installed in them, coded to the car. It is critical on a modern car to make sure the engine and other electronic systems in the vehicle are in good working order before attempting to repair an automatic as they are all integrated.
Whenever an engine or transmission check light appears on the dash, the vehicle should be scanned for the fault stored in the computers memory.
If there is an electrical fault present in the vehicle, it may go into a limp/default mode. The computer will stop driving the transmission to avoid damage and it will usually be sluggish on take off as it will be stuck in 3rd gear. If the car is stopped and ignition is switched off for 15 seconds, the computer may see no electrical fault and drive normally until the fault reappears.
With our diagnostic equipment, we can monitor all data streams of a vehicle such as solenoid activity, speed sensor outputs, commanded gears, torque convertor clutch application, etc as well as forcibly control them to test they are in working order.