The installation is for HO-Scale Tiger Valley Models RSC14. It uses T1 decoder and was performed by Jean Lacroix.
First, you will have to locate and remove all the screws that hold the body underneath the locomotive. Normally you have 2 screws in the front under the cab and 2 other at the opposite end near the steps. Remove the shell and the cab of the locomotive. Remove all lamps hooked to the motor or otherwise installed. If they are of 1,5 volts you should discard them and save them for future projects.
You will need to unsolder the wires that were hooked to the motor. You will then solder the black wire from the harness to one of the truck screw and the red wire to the other truck contact screw. After this is done, you have to solder the grey harness wire on one of the motor contact and the orange on the other. It is suggested strongly to use heat shrink tubing to cover all exposed nude wiring or soldering made between wires. You will find heat shrink tubing in electronic parts stores across the country.
Then, we will take care of the lights. I used Leds to replace the original 1.5v bulbs. Solder the blue wire from the harness to the white and yellow wires as per the instructions that came with your decoder. The lights were simply glued behind the holes for the headlight holes.
In the sample shown, the motor is a Sagami and is already insulated, so you do not have to bother to isolate it from the frame or the body.
You can use “Tack’NStick” adhesive (sticky paste) or double-sided tape, to stick the decoder on the locomotive floor. This leaves room enough to later add a sound unit to your locomotive. The green and violet wires can be cut and put electrical liquid tape at their ends.
You are now ready to reassemble your locomotive doing backwards what you have done in order to disassemble it.