4 wires, I did put power to the terminals, and the two outside ones powered the trucks. That was a couple of days ago, I believe they were the Brown and Green ones, if I remember correctly. I will be running RailPro battery power, I could have just looked into my other LGB Diesels which are all running RailPro and battery power, but I would have to remove the body shells to see inside. Thanks, I will wait for your answer, trainman

Glad to hear that Mrpicks!
How did it work when you set about to assigning it to the locomotive?

Well, I knew it was to good to last.....
Even though my track work is really quite good, this short wheel-base switcher needs a Keep-Alive to get across my diamonds without dying. With a Scale Sound Systems speaker under the hood, there was no way a Ring PBM-2 was going to fit. I've read here on this site that others have employed TCS Keep-Alives successfully, so, that's the route I went. I picked their smallest option, the KA2.
The only place I think it could fit was within the dead space in the center of the cab's interior. Here's a shot of what I'm referring to. The cab shell has been removed leaving the interior. The spot I'm targeting is that space in the center of the green cab interior in between the walls.
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Next I removed the cab's interior. Here's a shot of that.
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So, you have to remove/cut-out a piece of the floor so that the KA2 can be slid in from inside the SW1500 shell. Here I popped off the wall assembly from the floor and you can also see what I cut out from the floor.
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Unfortunately the KA2 is a bit wider that the space between the walls, so I popped the glue joint on one of the walls. Here's that.
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Then I glued everything back together.
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Does it fit? Yes it most certainly does!
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Here's a shot of the cab's interior reinstalled with the KA2 stuffed up into that dead space.
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Then it was a "simple" matter of connecting the wires and tucking everything back into the shell. Obviously this would have been way easier if I installed the KA2 from the git-go, but, it worked! Runs like a champ across my long 19 degree diamond!

Now that I've shown it's possible, you can do it too!

Do your trucks have 3 wires or 4 wires?

Are you running from track or battery?

I can give you the answer if you answer these 2 questions.

Your recollections are close.

Functionally, the LM-2S and 3S are pretty much the same.

• The LM-2S had 2 input wires but the 3S only has one (it got a negative wire instead). Since there was never a way to use both input wires on the 2S as a locomotive module this is a moot difference.
• You only had to use a bridge rectifier with the LM-2S if you wanted to use a keep alive. The 3S made the connections available on the LM itself so an external bridge rectifier isn't needed.
• DCC capability is determined by the firmware loaded into the LM. It's been a long, long time since I played with LM's on DCC but I suspect the LM-2S's capability is the same as the LM-3S. There used to be an issue about not being able to do consists with NCE but that was an NCE issue. I would imagine it is not fixed.

The 3S may also have a bit more onboard storage space; I can't remember for sure though.

- Tim