Here's a recent install I did in some Intermountain ES44ACs. With the 9-21 pin harness the number board and rear ditch lights did not operate. On the rear of the main board you need to remove the black wire and add a 1k 1/4 watt resistor to it. I used the rear output violet wire to operate them. Attached is various photos to show what I did. This first picture shows where to remove the wires. In both cases the factory wiring will provide the positive feed for the blue wire through the 9-21 pin harness.
This next photo shows where the 1k 1/4 watt resistor was added for the front number lights. The rear green (output 5) was used for these.
I this view shows where the black wire to the rear ditch lights was removed and attached to the rear (output 6) violet wire.
The heat shrink covers the 1k resistor.
Here the body has been placed back on the chassis. Intermountain has a round speaker housing that needs to be removed. This can be popped out once the radiator compartment is lifted off the shell.
When it's all back together this should be your results with all lighting functions working on the engine. Front view. For non flashing ditch lights you will need dual ditch on/off effect. This will send the same output to the front green and violet wires,(output 3 & 4).
Rear View
