Lighting Problem With SD45

 I can't find it in Barry's book ( 1st edition)

It's in there. it's on page 47 of there first edition.

It's possible that your engine's lights are connected to the PS2 board via spring-loaded contacts.

If you carefully remove the engine's cab, you should see little blocks, on the posts that are the places where the cab screws down, that have springs that rest on pads on the engine's chassis. Sometimes, these blocks ride up their posts and the springs lose contact with the pads, causing lights to be always off.

Thanks Barry, I'll check for the springs.

A feature reset should restore the lights, but since Markers go on and off together, sounds like the springs as Barry said.  Head light may be same or you could have burned out bulbs.

Just be careful reassembling the unit.  You do not want any wires pinched, especially any close to where the spring pads are, or under the body mount post.  G

Well the feature reset did nothing so I took the body off. There are no springs anywhere. The body screws go through the bottom plate and straight into the molded plastic body mounts. The wiring was not very neat and I  found two wires that at one time or another had been smashed by the body mounts. I was a little surprised at this since one had been pointed out to me when I took it to the LHS repair station in Burbank to get the PS2 board replaced. I thought they would have fixed that then but apparently not. Anyway I gathered it all up being as orderly as possible and put a zip tie around it and lowered the body back on. I powered it up and at first there was no change, then suddenly the rear marker lights came on but not the front headlight. I ran it around the layout and the rear marker lights would go on and off but mostly stayed on. So it looks to me like the problem is wiring associated, at least for the markers. The headlight could just be burned out. According to MTH I can get a new lamp and wiring harness. I'll have to look and see if this requires an engineering degree to get the old lamp out. At first glance it's not nearly as easy as my steamers. I'd rather not drive 90 miles for a lamp change though. Has anyone ever pried one of these microscopic bulbs out of a Diesel?

Before prying the bulb out, I suggest you unplug the wiring harness and test the bulb.  I'd use a 1.5V battery, it should light it sufficiently to see that it's alive.  I'd think it's more likely wiring, and if the wiring was pinched, it could have toasted the FET on the logic board.

Good suggestion. I'll try that. Is there any way to restore the wire if it has been squished by something? I guess I'm not grasping why they are so sensitive to the insulation being squeezed. Also, how many FETs are there on one of these things? The rear headlight works fine.  

These are 6v bulbs so you can use 9v quickly as a test.  How are the bulbs connected?  I would trace the rear marker light wires.  Should end up at a yellow connector. If the shell comes completely off they have to use spring connectors mounted on body post.  If not then connectors you have to disconnect.  Make sure pin has not pushed out.  

you can splice the damaged wire and recover in heat shrink or tape. If the bulbs are in a clear lens, you need to pull them out, after you test them.  Sometimes they come out no issues, other times they break and you have to clean the glass out of the plastic lens. I use a drill bit that I turn by hand to get glass out.  G