I've got no power to the main alt connector(that comes from the battery) and also noticed no tach.
This s/b basically a direct connection from the battery, no?

 

Do you have an S4 or S5 alternator?

 

S4 vehicle, S5 Alt.

 

The S5 alternator has a plug w/two wires. One of these wires is Black/White and it runs to the engine fuse box. Was this the wire you checked? If it was actually the thick output cable then that ties into the engine harness via a staple/clamp. It might have come loose. The battery has a smaller cable coming off of it that runs to the engine fuse box. The alternator cable splices into this.

And what came of the low voltage on the Br/W wire at the engine sensors? Did you rectify this problem or not?

Also, no tach signal means no trailing coil. Have you checked for spark at either of the coils. And if you haven't cleared up the issue w/the Br/W wire then neither coil should work which would explain why you have no tach signal.

 

It was the thick wire. I'll trace it to see if that staple/clamp came loose.

Last weekend I purchased a parts car w/a Microtech and xfr'd that to my car bypassing much of the wiring harness and the ecu.

I'll check that. If the tach signal goes thru the ecu, that may be the issue and I may have to figure out how to wire the tach to the trailing coil directly.

 

The Yellow/Blue wire from the trailing coil is for the tach signal.