The 'red and white wire', whatever color it may be, runs directly off the ignition coil in the engine compartment from my experience. Look at the top of the coil for a thin (16 gauge, about the thickness of other dash wires) red and white wire. If you see it, thats your red and white. If not, then you'll have to poke around and test by that coil to find out what the color wire is that sends signal to the tach. Once you find the signal wire in the engine bay, look for that color wire in the dash.

Dan

The only wire i found was that gray one. I've found a couple references to some peoples tach wires being gray? If i jab a test light in that sucker, what should happen? a pulse that goes with the RPM? What are the chances that my tach is just plain old hooped? I guess tomorrow i'll just run a new wire to the negative coil. That's where it goes, right?
Is there any bench tests i can do the the tach to make sure it's not the culprit?
THanks guys

K
Found the gray wire, connected it, connected all the wires back up, start car, no tach working. Everything else works in the cluster, including the new small clock....... Bad tach? Please don't tell me it's a bad tach..... anything i can do to test this?

The tach wire on my car is GRAY in color. I have seen other 240/260's with the red/white wire but that maybe for later years. Anyways the wire for my tach comes out of the main harness/bundle of wires behind the instrument cluster and the wires comes out of this harness/bundle from the left side; i.e. closer to the tach than to the middle/right of the cluster. The tach wire has a female spade connector already attached and it connects to the lower spade connection on the tach. The upper three connectors on the top of the tach are to power the small clock via an extra wiring harness or you could could cut your own wires. I had seen a tach at one point that had two lower spade connections at the bottom-backside of the tach. I gave this tach to a friend and he told me that if he hooked up his tach wire to either connection the tach worked fine. Hope this info help you out. Good Luck!

Sincerely,

Julio Meza

1979 264GL B27F 122K

Features Added:

BW55 To M46, Central Locking System, 25mm IPD Front Sway Bar, 81+ Dash W/ Oil & Ambient Temp Gauges In C, Oil Pressure, Volts

Next Project:

+Cruise Control