Tac Not Working on Newly Purchased 70 RR with Rally Dash

[soundhd]

Recently purchased a 70 RR with the Rally Dash. TAC is not working. The The gray colored wire from the TAC to just outside the firewall is there and connected to the TAC on the center connection point on the back of the TAC. The engine bay TAC wire is missing so I made temp one and connected one end to the TAC wire and the other to the Negative side of the coil but when I started the engine the TAC needle did not move (it is sitting at the 5500 point on the TAC). The wiring diagram shows the other wire connected to the TAC runs to the accessory fuse on the fuse panel....all the accessories are working so I assume the 12 volts are there with the key on.......Is there a way to "test" the TAC to see if it is working ok while it is in the dash?.......looks like a major job to get the Rally Gauge Bezel out.......that's going to be my next "how to" posting....

thanks


Update; Realized it is not a Tic Toc Tac afterall but a Rally Clock.....still need to get it out.....put up another posting about replacing a Rally Clock with a Tic Toc Tac........

 

[Photon440]

The factory tach isn't a world beater at the best of times. Put in this aftermarket circuit board and be done with it.

http://rt-eng.com/rte/index.php/Main_Page