Turn signals

[Jack Innes]

Hello, I am trying to figure out the turn signal connections on a military truck built in 1969. The switch is made by Spartan & has 6 wires coming from it. The relay box has no markings but may be something common to other 24 volt military applications, most of the other gauges & switches are standard looking. The box has 2 connection bars one with 6 connections & the lower one has 5. The brake light switch is not connected to anything at present. The signal system looks like it was on the truck from the factory.

When the main light switch is on "Brake light" the relay makes flasher sounds & the indicator on the column flashes but nothing else works. The signal/brake bulbs all work when energised at the box with a jumper.

Does this sound or look like anything common to other vehicles?

Thank you for any suggestions.