Well i don't even know if I should post this but the alternator problem is solved. After more hours of reading wiring diagrams and playing with the multimeter i thought it was time to get back to basics. So i started by removing the harness plug from the rear of the alternator. It came out a little too easy, turns out whilst i had the motor on the stand and was fitting the engine harness i didn't plug the connector in correctly. All fixed now and charge light is working
For the tach i hooked the tach wire from the ecu up to the standard gauge and used the resistor to bring it back to correct reading, as per the thread i linked to on the previous page.
Cheers
