Help Needed reading schematic
 

Here is my dilema:
I have a 1977 911S that originally had a 2.7 in it. I have transplanted an '80 SC 3.0 into it. I can't get the tach to work. I removed the original tach and traded it for a tach from an '80 SC 6pin ign unit to match what is in the car. The existing wire harness has the Blk/Vt tach lead shown in the schematic but also has another lead from the same terminal. I can't make out the color of this second lead. Also what is indicated by the little box that is labeled "I 25" and "I13"?
http://forums.pelicanparts.com/uploa...1190762371.jpg
TIA

I just checked my Haynes manual. It only has the 81 SC, and doesn't have the second wire. The I25 and I13 refers to diagram #1, line #25 and line #13. You should have several diagrams with roman numerals on them. The line numbers are at the bottom of the diagram. That's where the other end of the wire is located in the diagrams.

CDI unit and rev-limiter relay ... both in section I of the schematic, cuurent traces 25 and 13, respectively:

http://www.pelicanparts.com/ultimate...hematic-1s.jpg

I see!! Thank You guys.

I couldn't get the tach to work in my 73.5 either. It turned that I didn't have the 6 pin connector pushed far enough into the CD box. I wasted hours troubleshooting something which should have taken seconds.

It Works!!!! You guys saved me $300.00 (if I had to send it out to have it fixed)
Thank You Don and Warren.