This is a great example of an install in a high quality Athearn engine.  Many Athearns present a challenge in that the frame carries power.  As with DCC decoders, our module expects the power source, motor and outputs to be isolated.  The key points with this engine are that the motor was resting on the frame at the bottom and there was a power clip connecting the top end of the motor to the trucks.   Below are the steps to isolate the individual components:

  1. Remove the power clip that connects the top end of the motor to the trucks.  This simply was held in by a clip and pressure.  
  2. Remove the motor from the frame.  On our locomotive this was just a rubber base.
  3. Place a piece of kapton or electrical tape on the frame where the motor rests.  The key is that the motor does not make contact with the frame.
  4. Solder the orange wire from our harness to the metal clip on the bottom of the motor
  5. Solder the gray wire from our harness to the metal clip on the top of the motor
  6. Solder the purple wire from our harness to a positive place on the light
  7. Solder the first green wire (next to the blue wire) from our harness to a negative place on the light
  8. Wrap the light in tape to isolate it from the frame
  9. Solder the red wire from our harness to one of the truck power clips
  10. Solder a jumper wire between the two truck power clips.  This ties the trucks together.
  11. Solder the black wire from our harness to the light mount, which in this case was a clean ground connection.
  12. Connect a second output if desired

The pictures below were taken at the end of the install, so some of the steps are hidden with electrical tape.  The key points are to completely isolate the motor, completely isolate the outputs and find clean power and ground lines.