The More

Actually, it is an easy project for most diesels. I am using prewired 0603 smd LEDs but you can wire your own or use  an 0402 with magnet wire. The effect is subtle so I would avoid the 0805 and 1206 varieties due to their brightness. An exception would be if used with the Tsunami 2 and its variable brightness outputs.

Start by cutting a vertical channel, slot if you will, in the side edge of the locomotive main frame to recess the wires going to the decoder. I have used both a Dremel with a metal cutting disk and a suitable file. Obviously the Dremel is quicker but messier. If you leave the motor installed, protect the motor and truck gears from metal chips and unintended contact with the cutting disk. Masking tape makes an adequate shield.

The Dremel only required about 10 seconds per slot working slowly and accurately. Target about .0625-inch depth but this can vary with the wire gauge attached to the lights. When done, brush away the metal chips. You need enough “room” for the soldered wire joint where the light will sit on the frame. This is an older Proto 2K with the ground light mounted. Insure the LED is as parallel to the rail as possible so the light projects down, and not to the side.

 
This is the frame of an older Athearn RTR SD40-2 and I extended the vertical slot across the top of the frame as the bottom of the cab covers this area.

This is a current generation Genesis SD70 and the bottom of the shell allows a simple mounting location by drilling a small whole in the area beneath the cab. Another plus is being able to orient the LED and secure it in position while the adhesive cured. I applied Kapton tape over the LED while the adhesive cured.

Like magnet wire, the wire on these LEDs is small and has a mind of its own. As the project included changing the incandescent bulb headlights and ditch lights to LEDs, the cab interior was getting crowded with tiny wires. I used small diameter shrink tube (green in the photo) as conduit to route the wires to the uncluttered rear of the decoder. I used rear light common pad with suitable resistor as power. The function wire was also routed from the rear of the decoder to the aux pad.

Completed E-units at the station this evening.

Curious

what you use for adhesive for the LED.  I'd like to just put some adhesive on a numberboard and push the SMD LED into it to secure it, but I'm not sure what would work without damaging the SMD.

@ duckdogger

Please contact me.

amsnick2000@yahoo.com directly, not through the useless email function of this site.

@Dave

CA will work but is too permanent.  I’ve used Formula 500 Canopy glue for the smd to acrylic and Rubber cement for both smd to acrylic and to tack the wiring in place on the locomotive.  Looks like duckdogger is using a translucent glue that disperses light better.  I like that effect.  Both of the above are somewhat translucent when dry.

Nick

Thanks, Nick

I'll give one of those a try.

Nice

@Dave

Agree with canopy cement and Microscale’s Krystal Klear works well, too. Another option for a quick grab is Bondic. 

Additional locos finished

The Genesis FP45s added a bit of complexity to managing the ground light wiring due to the frame layout and speaker mounting. I added small pieces of shrink tube, as on the E-units, to act as conduit for the ultra thin ground light LED wires. I used clear silicone to secure to the frame.

Another station photo of a couple FP45s and an SD40-2 with ground lights.

You know, ground lights are

You know, ground lights are something I never noticed before until I was on a canoe trip as a teen in California and were were camping near/under a railroad bridge.  I remember it being dusk or dark and a train slowly crossing the bridge and you couldn't miss the ground lights.  I've totally forgotten about them since then until reminded here.