Yes, I did not mess with the settings. Just got around to it late at night tonight.
I dug up an old motherboard, nipped off a couple of the prongs those ribbon cables plug on to, poked them into the wiring loom side plug thingie that feeds the tach. Figured black was earth, got a voltage on the white wire, nipped the white wire (and put some heat shrink over the nipped ends to ensure no stray circuit)…
Plugged the tach wires and cluster loom back in …. Gas tank read empty (was full) gauges all blue though… pulled it back out turned the oil and alternator lights back to incandescent , faffed with the flimsy printed circuit board for an hour…. Put the cluster back in the car… haven’t put the crash pad back in, I want to check the speedo works because I had a hard time getting cable back on, and the temp gauge (it is cold - needle doesn’t move) I will check tomorrow before I close it all up.
Thanks for all advice!
The dish of the base gauges catches slightly more light than the flat XR7 tach, but it aint bad (photo exaggerates it).
I am so digging the blue now though.