Tach help

[kretzj]

I am completely perplexed by this tach problem.

Background:
1972 911 converted to 86 motor with DME
1976 speedo
1986 tach

Problem 1:
My speedo was sticking so I had it serviced. I reinstalled the speedo and now my tach does not work. The turn signals work and the high beam light works only if I have the gauge out and touching the steering column. If I pull the ground wire from the back of the gauge and touch the gauge casing, the light works. What is wrong with the grounding in this gauge? The damn thing worked before I fixed the speedo!

Problem 2:
The tach worked before the speedo removal and I noticed the red 12V line came off the tach during the speedo install. I tried installing it back on through the speed hole in the dash and touched ground (case) a few times. Is it possible to blow the tach this way?

Is there an easy way of testing the tach to see if it works to isolate the gauge itself?

The wiring scheme is :
1) black from DME (added during upgrade)
2) purple from DME (added during upgrade)
3) open
4) original 1972 Black/Violet wire (?)
5) Red/White 12V
6) Brown
Hg) open (what is this conection for?)

Any help would be appreciated.

Jon

[snbush67]

Maybe one of these threads will help.....

http://forums.pelicanparts.com/show...chometer+.7+3.0

http://forums.pelicanparts.com/show...chometer+.7+3.0

http://forums.pelicanparts.com/show...chometer+.7+3.0

[kretzj]

bump