Lionel TMCC Cab Lights...

With TMCC you only have one item you can control independently, either smoke, cab light, or mars light. If you want to keep control of smoke you have to build your own independent circuit. A fairly easy one is put an amplifier (op amp) that senses motor voltage. When voltage is applied to the motor and the engine is moving the amp opens a relay/switch, that turns off power to the cab lights.

One of the many drawbacks of a closed system like TMCC/Legacy is the difficulty of adding your own features unlike DCC where decoders and controllers will allow you to add many.

Pete

With respect to the "overpowering" cab lights on some of the TMCC-era F-3 scale engines, I just did a quick solution on mine, and snipped one of the wires to each of the cab bulbs. There's enough light coming back from the headlight area to provide subtle lighting in the cab that's acceptable without any cab lights. Without the cab light bulbs, there's not much light visible in the cab when running with the train room lights on normally, which is good, but there's some illumination that shows in darker lighting conditions.

On some other types of engines, I removed the bulbs from their positions in the cab area and pulled them back inside the body away from the cab.

@breezinup posted:

With respect to the "overpowering" cab lights on some of the TMCC-era F-3 scale engines, I just did a quick solution on mine, and snipped one of the wires to each of the cab bulbs. There's enough light coming back from the headlight area to provide subtle lighting in the cab that's acceptable without any cab lights. Without the cab light bulbs, there's not much light visible in the cab when running with the train room lights on normally, which is good, but there's some illumination that shows in darker lighting conditions.

On some other types of engines, I removed the bulbs from their positions in the cab area and pulled them back inside the body away from the cab.

Those over bright cab lights really highlight that red interior on the SF units. That needs to be addressed as well.

@Jeff T posted:

I have several sets of F3's and the cab light on constantly is annoying.

With all the electrical guru's on the forum, of which I am not one, has anyone figured out a way to have the light go off when the engine is in motion??

One of those questions that needs to be asked every couple of years! Thanks!!

Au contraire!  I did this years ago!  Here's a thread where I described my custom module and how to control the cab light and smoke intensity with it.

Altas F-3 interior cab light

The module described does the automatic cab light control and also changes the smoke intensity, low when stopped, full when moving.