MTH B units, PS1 -PS2 plugs

No. The plugs on the PS=2 version are ten pin plugs, the Protosound version is only four plugs, as the slave unit in a Protosounds trailing unit is basically a DCRU, and the current for the DCRU comes from the lead unit. The only thing that the trailing unit uses the rollers for is to actuate the lighting, but the headlight is still controlled from the lead unit, as is the coupler. This is oversimplified, but the short answer is No. 

The 4 versus 10 wire is correct when the trail A is a powered unit in PS-2.

 In a PS-1 or 2 the trail rollers still power the slave board.  For PS-1 the DCRU is powered by the rollers, what is jumped out is the switching logic. 3 wires control how the DCRU relay switches the motor relays as directed by the lead PS-1 top board.  Coupler is the fourth wire also controlled by the lead top board.  The Trail directional light is still powered by the DCRU via diodes that create the 1.4 V drop when the motor is in reverse.  G

Thanks for the info.

So, would a Railking PS2 F3 or FA  have the same wiring harness in a non powered B unit as a Premier PS2 F3 or FA  B unit? The plugs would be all the same PS2 10 pin plugs, maybe just the length changed?

I would guess a PA or FT would be the same too?

I was really looking for some B unit parts, the wiring harness and a thick coupler to replace the thin coupler. I thought it might be cheaper to get a used B unit for parts than ordering the parts from MTH.

I was thinking about installing the wiring harness in a non powered geep to get an A-GP-A consist.  

Dan

Dan  Some of the RK RTR PS-2 engine only had a 4 wire connector exiting the Lead A for the Trail A or B unit that are dummies.  The reason is the only thing needing control was the light and coupler.  You only need three PS-2 wires to control those 2 items.

If you PS-2 Trail A is a dummy you can easily use the 4 wire harness to control head light and interior light on one circuit, the coupler, and number boards.  2 light circuits, coupler and common power feed to all three.

The best bet is to ask the seller what type of harness is coming out of the B- unit to know for sure.

The MTH Part number for the PS-2 B unit pass thru harness is BC-2100070. You could order this.   The issues you may have is one end is just a plug and depending on the model you may have to pull a wheel to fit this through the truck.  The other end is a PCB receptacle.  Normally mounted to post that come off the B unit truck.  If the B unit doesn't have them you need to add them, some times by drilling and tapping.  G

Thanks GGG, It is always more involved than one might think to tweak a project.

That is why I think I will look for a used B unit to take what I need. (seems a PS2 B unit may be available from time to time for the same price as MTH parts and shipping.)

I found the manual on the MTH web site that has the connector wiring harness and the coupler listed. They only list one number for a coupler, my B unit now has a standard thick coupler on one end and a thin coupler on the other. The thin coupler is higher and will not allow it to stay coupled to freight cars or even the FT units I have. I believe it is for easier mating the connectors plug together, but looks like it  could be replaced with a standard coupler and still plug in OK.

I will further investigate and see what I need.

Dan