# Wiring Issue MTH



## bstanifer (Dec 14, 2011)

Hello All. 

As all may or may not have known by now I have took a leap and purchased an MTH Dash 8 engine. I am trying to wire a switch (ON-OFF-ON) so i can run regualar track power or MTH at the flip of a switch. Below is my suggested problem.


I just purchased a MTH Dash * for G Scale and have run into a problem. I was wanting to put a switch (ON-OFF-ON) so I could run MTH but could also turn and run regular track power if wanting to. I have a MRC Power G Transformer and the TIU. I have tried wiring the way that makes sense but in no cases can I get the track to work with the TIU. Either Way I switch the switch the normal track power runs the engine. Thanks!



Brandon


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## John Allman (Jan 2, 2008)

I dont quite understand. Where are you installing the switch?


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## Trains West (Oct 4, 2008)

one would *assume* that you are useing a double pole double throw center off.....


output from dc power hooks to one end mth power hooks to the other end and the output to the track is in the center


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## Greg Elmassian (Jan 3, 2008)

I'm a bit confused. I thought (at least from my experience) you can run an MTH unit on regular DC, i.e. vary the track voltage and you vary the speed. Also, the unit will work on a constant track voltage with the signal from the TIU added. 

So, the only place I could envision a switch was on the track side, i.e. change the track power from constant to varying and cut the TIU in and out of the circuit. 

Am I missing something here? 

Greg


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## jebouck (Jan 2, 2008)

You are correct, Greg.
A friend first ran his MTH GS4 (right out of the box) on regular track power using an LGB Jumbo.
Then he bought the MTH controller and ran it using that and the LGB power pack.
And now it is completely converted to Airwire/Battery.


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## Trains West (Oct 4, 2008)

I asumed thathe was trying to get to more fuctions not gust run ....

I also assumed that he is using a fixed power brick to run the TIU this could be a wrong assumtion on my part 


mth proto two g instructions are below 


* Using DC Power Supplies
* It is important to remember the DCS system was designed for inside layouts. If DCS is
used outdoors on One gauge or (G gauge) layouts, please make sure the system is protected
from the weather (rain and snow for example). In addition, DC power will NOT
pass through the TIU Variable Channels. Therefore, use only the Fixed 1 & 2 Channels
with DC power supplies. Also remember the polarity is critical to DCS Command operation.
The positive (+) rail carries the digital signal. You may have to place the engine on
the track in the opposite direction if the engine does not have a polarity switch. It is also
very important to keep in mind the positive output (+) from the DC power supply must
be connected to the positive (+) input terminal on the TIU Fixed channel to carry the


DCS signal to the track.


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## bstanifer (Dec 14, 2011)

I am wiring on the DC side. I have other engines besides the MTH and was wanting the capabillity to run just regular track power. All are on the right path. 

@TrainsWest Yes wanting to put in a double pole double throw ON-OFF-ON. 

Just having problem getting it to wire correctly.


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## Trains West (Oct 4, 2008)

so what are you using to power the tiu?

if the information posted so far has not helped you fix the problem you are going to need to describe or draw or take a picture of what you have wired so we can figure where you went wrong .....


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## bstanifer (Dec 14, 2011)

Sorry for Confusion. I am powering the TIU using MRC Power G. The switch does not really even work either way it is switched the track runs normal track power like the TIU is not even there. Could wires be switched on input and output sides of TIU? 

Thanks, 
Brandon


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## Greg Elmassian (Jan 3, 2008)

Reverse the direction of the loco on the rails... otherwise the loco will run at full speed all the time. 

Greg


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## John Allman (Jan 2, 2008)

You also need to check that the input into the TIU is correct. If, as you say, "it is as if the TIU isn't even there"... then it probably isnt because you have the input to the TIU reversed. Do that before you reverse the engine on the track. If the remote doesnt read the engine after you reverse the input, then change the direction of the engine on the track.


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## bstanifer (Dec 14, 2011)

@All 

I reversed the input and output for the wiring going into the TIU and then made sure all track contacts (every 20 feet) were on the same rails all the way around respectively. Fired it all up and Presto! it worked. Thanks to all input involved and for any that provided insight to this issue. 

Brandon


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