KB886: Installation of Digitrax Wired Decoders in a Kato GP35 Diesel HO

This article was last updated on Jan. 30, 2012, 5:36 p.m. | Print Article | Leave Feedback

Note: These instructions cover the hardwired installation of any Digitrax decoder with wires into a Kato GP35 H0 Diesel. Currently, the recommended decoder for current production GP35's from Kato are the DH163K0 board replacement decoder.  Using the board replacement decoders are much simpler and cleaner installation than the one described here.

Tools Needed for Decoder Installation

You'll need a few simple tools:

1. A soldering iron, preferably temperature controlled.

2. Solder

3. Screwdriver

4. Small diagonal cutters for cutting and stripping small wire

5. Tweezers

Motor Isolation for Kato GP35

Carefully remove the loco's shell and weight.

To isolate the motor, disconnect the brass strips (motor brushes) from the track pick up rails. Bend them out and cut them short enough so that they won't touch the pick up rails.

Decoder Placement

The best decoder placement in this loco is at the rear since it will be away from all heat sources inside the loco and there is plenty of room.

Cutting & Soldering the Red & Black Leads

Cut the red and black power pick up leads to length and solder to the track pick ups. Red to the right or engineer's side and black to the left or fireman's side.

Cutting & Soldering the Orange & Gray Leads

Cut the orange and gray motor leads to length and solder in place. Orange to motor + and gray to motor -. If you want to wire your engine for permanent backwards operation you can reverse these leads. You might do this if you always run this engine backwards as part of a consist.

Lamp Board Modification



Remove the lamp board and cut the trace shown using a Dremel. Then cut to length and solder the white, yellow and blue wires to the lamp board as shown. This will give you constant brightness directional lighting.

Function Leads

Since we are not using the green and violet function leads, we clip them short. If you think you will use these in the future you can leave them a little longer and tape the ends so they don't touch anything else.

Reinstalling the Weight


Replace the weight and tuck in the wires so they are not pulled loose when you put the shell back on

Finished Installation

That's all there is to it! Obviously, there are locos that are more difficult to install decoders in but, with a little practice, you'll be a pro before you know it!

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