T140 headlamp wiring

1977 T140 Bonnie....Same problem here even with a new harness and new connections. Turned out to be a short (grounding problem). Ran a wire from the turn signal arm (inside nut) and the nut holding the head light bracket to the forks..Fixed...You can hold a screw driver between the two points for a test....The bracket is mounted with rubber insulators.... In short, the headlight bracket needs grounding to the forks...... Next problem the single indicator light on the headlight shared by the left and right turn signals did not blink..... Light Fixture (holds the bulb) has two inside side connections or poles. Juice comes in from the right, the left act as the ground. Juice comes in from the left the right acts as the ground. One side (left) was not connected between the plug in connector and the light fixture. Since the wire runs back through he harness to who knows where and then reappears out the other side of the harness I could not get to the wiring. so, I ran a 6" wire from the left turn signal plug (inside headlight) to the left bottom side of the fixture which was the bad connection.... Problem solved. Good luck hope this helped, but remember. Triumphs are like people. No two bikes can be repaired in the same way for the same problem.