Wiring schematic

How about some pictures.  Are they out of a connector or desoldered from the tether connector?

There is a diagram in the PS/3 Steam Upgrade Kit.  Note that MTH has NOT been consistent in their wire colors with the kits, so trace the wires out before you decide where they connect.

I started to change the headlight bulb, pulling out the plug the whole thing came out, Both the male and female parts of the plug, Now having to take off the the boiler, I found three loose wires two pink and one gray. I figured that the two pink wires would be for the headlight. I soldered the wires back on the female end. Installed the new bulb, started the engine up, no headlight, in reverse the red light comes on. On further inspection I found the gray wire. Just to try things I hooked one pink wire and the gray wire to the headlight and the bulb lights tried the second pink wire to the gray and the light comes on. The only problem with that  is the engine has not been started. The light is getting only track power.

I hope this shows my problem more clearly.

Thanks, David

Who did the upgrade?  Ask them?  With Premier engine there is a CV board and usually still required for lighting.  I would be careful doing what you are doing.  Short the 5V or PCB wire to chassis and you will damage your board.  G

Never a good idea to randomly start connecting wires without understanding what they are for.  It's a good way to fry expensive boards.

Revisiting, this is a PS-2 5V engine with board in the engine.  So did the repair install a new PS-32 board in the engine and keep original wiring or did someone do a tender upgrade and gut the engine.  You need to take shell off and see what you have.  G

GGG, I will find out how it was done

Okay, I was told that the new board was installed, and the original wire was kept. Also, on checking the two colors of the wires they are two pink and one light blue.

David

the blue wire is for the headlight, usually the PV wire is purple for the other wire to the headlight, as Gunrunner has said MTH does not always install the correct wire harness colors!

Alan

Pictures!

This is not a kit Alan, this is PS-32 replacement of a 5V board in the engine.  Are you sure the pink are not Purple?

You do need to post pictures.  The FEF had many light features all driven off the board inside the engine shell.

Normally a Light Blue is head light.  A dark blue is PCB ground and used for other things like tach and smoke switch.

The + Voltage for bulbs is normally purple.  Sometimes a connector may have a double purple because it jumps + voltage to another connector.  Wires on that engine can get brittle.  You have a lot packed into the front.  HL, Rev Red light, markers and smoke unit.

Gray would be 5 Volts for marker or Smoke fan motor.  Do markers light?  Smoke fan motor work?  BECAREFUL with the 5V gray wire, that can kill the board if it touches chassis.  G

Okay the light blue wire is for the headlight; it is possibly the other two wires are a faded purple, because of age so does that mean those two wires get joined together and then go to the other lead on the headlight?   Markers work as the smoke unit and the reversing light. I agree that you need to be very careful with the wires because of the age of this engine.

Thanks for help, we must be getting closer to fixing this problem.

David

If they are purple than yes, but that means there is another light out some where.  Cab or Fire box?  What about the gray wire?  If that is off something is without power?  Why can't you post a picture.  G

Okay, I reopened the engine again and three wires are two purple and one  blue. Attached is a picture of the wires. My wife had to show me how to do it. I hope this helps.

David

It doesn't help me.  This is what I get.

You can post pictures directly to the forum by clicking on the Add Attachments link at the bottom of the message box.

Here is another shot of the wiring

David

So the single purple/pink wire(PV) that is in the same 12 pin connector as the blue wire goes to the Head Light connector. Blue wire is the fet controlled return for the HL.

The other purple/pink is in the 4 pin connector and is the Positive Voltage (PV) to the Smoke unit heating element.  It must have broke off. So you have smoke fan running but no heat so no smoke.

Both purple are the same source of PV, so either will run the HL with the blue, but best to put the 4 pin purple on the smoke unit.

G

Guys, thank you so much for your help.  Plus I learned how to post pictures. Thanks again.

David

GGG, out of curiosity what does fet controlled return mean?

@hobojoe posted:

GGG, out of curiosity what does fet controlled return mean?

So, in a DC system, you might think of putting a switch or transistor in the + side of the circuit BEFORE your load. This is called high side switching. The catch22- that requires a P channel MOSFET transistor which always has higher ON state resistance and also complications with the gate drive.

So, most modern recent electronics use N-channel MOSFETS switching to DC- or basically common DC sometimes called board ground. The load or device is connected to a positive DC source. The return from that device goes to this MOSFET that then is connected to DC- completing the path. This is done because both the gate drive of the FET is simpler for N-channel, and lower ON state resistance means the transistor can handle more current without heating up and wasting energy.

Again, key below in the picture is, the load or device is connected to the positive voltage source all the time directly. The return leg of the load then goes to the N-channel MOSFET that can turn on and off the connection to DC negative.

https://www.youtube.com/watch?v=g8I_upSEGz0

Fet stands for field effect transistor. 

So, does it make a difference which wire on the HL the blue wire goes to?

@hobojoe posted:

So, does it make a difference which wire on the HL the blue wire goes to?

No, being an incandescent bulb it doesn't care but the more important part- neither wire can connect electrically to frame. The entire light bulb socket must be isolated from frame.

Thank you.