HD Mini Tachometers

I'm trying to put a HD mini tach on an '07 FLSTC. I am not sure which wires go to what, though. I assume (!!) that red is hot and yellow is trigger, but I'm afraid of ruining the tach if I'm wrong. I dont' have instructions since the tach came off an older FLSTC.

Any insight?
Thank you!

I confirmed the colors - and found a 42 photo installation which should be able to lead ANYONE through the process.
http://www.shareaproject.com/pages/projectThumbs,p,173,00.html

Thanks!

[Mike]

Just to be thurough, pink (in your case yellow) signal pickup should go to pin location #3 on the speedo connector, not at the ECM. Power (red, new orange/white) can be picked up at the fuse block at an unused blade location. Ground (black) should go straight to frame/battery. Scotchloks on the speedo wires scare me. The serial buss is very sensitive to the signals from these wires. The reference install does not indicate which pin terminal the signal wire is put into on the ECM plug.
Thanks, mike