msd install

Rouxzy · 03-22-2003, 01:50 PM

I installed an msd unit today and one problem arose. The tach does not work. In Wayne's 101 projects he says to hook up the black with a purple stripe from the cd box connector to the tachometer output on the side of the msd unit. I have a 3 pin connector, one red and two white wires. Can anybody tell me what to do to get the tach running?
Tom

jabb · 03-23-2003, 04:41 PM

do you have the MSD convertor box for the tach signal ??

CamB · CamB's Garage

Wait wait wait. Don't use the tach adaptor unless you need to. Some cars definitely do not need it.

What you need is to find the tach's black/purple wire. Wiring diagrams for other cars are at http://www.pelicanparts.com/911/911_Parts/911_electrical_diagrams.htm

If anything, your car will be like the '73. That appears to have the tach wire running from the points.

jtkkz · 03-23-2003, 06:38 PM

I did the exact same thing and the tach stop working. I have a 1973 911T

I did install a tach adapter, does this mean i could have messed up my tach? Would it have worked if i never installed a tach adapter.

Would it still work if I remove the tach adapter?

Iam thinking of sending my tach out to North Hollywood Speedo to change the circuit board in the back side of tach.

03-24-2003, 11:09 AM

On my '77, the tach works by connecting the MSD tach output to the black/purple wire on the white, plastic, "t" shaped, three way connector that comes-out from under the metal electrical regulator panel. It appears from the wiring diagram that the output from the distributor points splits: one wire goes to the white trigger going into the CD box, the other goes to the tach via the white plastic connector.

Rouxzy · 03-24-2003, 03:33 PM

Thanks for all the info guys. I found the wire. It is right where ejc-77-targa said it is. I was told from a certain Steve from Oregon that it is in there. Just traced the wires from the 3 pin cd plug back until I found the black with purple wire. I originaly hooked it up without the tach adapter and it ran fine, at least I thought. The readings were not consistant. I then put the tach adapter in with much better results.
Tom