E Unit wiring diagram

What engine is this from? I haven't seen the blue wire on the right before.

(6-28906) American Fire & Rescue GP20 Locomotive w/ Horn #209

Shame on me for not taking a picture before taking it out. I didn’t realize it had the spare blue wire until after the fact. I pulled it out to install a cruise lite board, but would like to know what goes where incase I need to use it in something else.

Seems to be too many wires.  Usually, there are six, two for the motor, two for the track power, and two for the reverse lockout switch.  Don't know what a 7th wire would do...

This engine was never opened prior to pulling this board out. I updated my last post with an image of the bottom of the board. 

Where's the drum and the solenoid?  

Is it a pass through connection for the cab lamp? Was it connected to a wire nut?

There were wire nuts on some of the wires, but I don’t remember which. The wire is tinned. It has the cab light, rear and front number plate lights.

It does not have continuity between it and the pickup. It gives a resistance reading. 

I have seen a few of these with 7 wires. If I remember correctly, they were the 105-1 unit instead of the 103-1 unit. They had the extra wire so they could be used on the double wound fields in some of the Pullmor motored (early 80's?) MPC diesels (single and double motored SD40's). I recently had to replace one of these boards for a customer and the part was still available at the Train Tender. I couldn't believe they could handle the current, but it did. I think they output DC so they could be used in can motored locos as a substitute for the 103-1 if wired correctly.

The only other thing I can think of is power input for the electronic horn circuit board.

Any guesses on what to do with the spare wire if I put it in a unit? Try capping it and leaving it unhooked?

Does anyone know what this does on the board? The wire is attached to the back of it.

Looks like it's a diode. The wire is probably for directional lighting.

WftTrains posted:

Where's the drum and the solenoid?  

They were in the Thanksgiving Day Parade !