TCS T4X, HO Scale Motor Decoder:
The T4X has added Blue and Black/White wires to use a KeepAlive device. This model now includes a 2-pin JST Plug for the KA-P Family of KeepAlive® devices. This decoder may be hard-wired or plugged directly into any locomotive with a 9-pin JST plug. The T4X may be used in locomotives with ditch lights and forward and reverse headlights.
 
Note: As of August 2022, All T4 decoders now come equipped with a plug/jack for a Keep Alive® with the corresponding connector.
 
Harnessed variant SKUs of the T-series have also been discontinued. If your locomotive is equipped with an 8-pin NMRA plug, you should consider the DP2X, or use the T4A with an adapter harness which can be found under our Harnesses section. 
 
Back EMF Load Compensation: Provides superior slow speed control and high performance under load.
Quiet Drive: Super-quiet motor control for "buzz" free motor performance.
DC Mode: Decoder will automatically detect DC power. You can also configure how your lighting effects function on DC.
RailCom®: This feature allows the decoder to talk to the command station. RailCom supports expansion for new features.
Variable Momentum: Allows you to make custom acceleration and deceleration curves.
Incandescent Bulb Support: This decoder can be used with 12 Volt bulbs.
Function Remapping: Buttons 0 through 12 may be used to control the lighting functions of this decoder.
Programmable Lighting Effects: Choose from 20 separate user-programmable lighting effects!
Dimmable Brightness: Configure multiple different brightness levels for your LED's or incandescent bulbs.
Decoder Lock: Feature which prevents accidental/unwanted programming while activated.
Airwire™ Compatible: Fully compatible with Airwire™ operation.
User-Loadable Speed Tables: Configure custom speed curves and set speed limits.
 
MSRP is $21.95. (Picture courtesy of TCS.)