Help with wiring diagram

Has anyone had any problem reading MyMopar.com wiring diagrams? I'm trying to diagnose an ignition issue and studying the diagram for my 74 challenger. On nearly every diagram I have looked at, only E-bodies have a second wire on the neg side of the coil. The first one, a black and yellow, goes to the ECU which seems common to the other diagrams. But the second wire (than other non-ebody diagrams don't have, traces down to the bulkhead connector but there is nothing connected to it on the other side. What's up with that?? I can't say for sure now (Its dark now) if mine, indeed actually has this gray wire. The only gray wire I'm sure about is the one that goes from sender to oil press gauge.
Anyone else have problems with mymopar.com's wiring diagrams??

Thanks
Scott

that extra wire on the coil neg pri would have to be the sense wire for the tach

The brown wire cames off the gray and goes to the tac on the 74 rr http://www.mymopar.com/downloads/1974/74SatelliteRoadRunnerA.JPG

D'oh! Now there's an "Ah ha" moment!!

Thanks
Scott

For me it would be a "Da" moment as I seem to have more of them as I get older. Ron

Those are basic diagrams. Check the FSM for a more detailed easier to read breakdown and it'll also have separate accessory diagrams for tach wiring.

I can tell you why those diagrams do not have the tach wire going to the tach. Those diagrams were taken from a CD that I put together several years ago from mostly National Service and Mitchell manuals. Those manuals did not include rallye dash wiring. You will find the rallye dash wiring in their 1970 diagrams as that is from a factory manual.

Yes, I copied those diagrams and sold the CDs. One of their members bought a CD and immediately published them on the MyMopar site.