Installing Tach Cluster And Have No Brake Lights,dash Lights Wipers Palsing Up&dn ,etc I Think My Problem Is Grounds There Are 3 Black Wire Round Terminal Ends Not Sure Where They Go. Any Help Would Be Appreciated.thank You. Phil

I believe they attach to the parking brake

Rear brake lights don't use a ground under the dash. Ground for them is in the rear of the car.

One to e-brake braket, one to metal dash support, drivers side of steering column cutout. Last one goes to metal housing on the dash cluster. Also there should be a metal ring around the headlight switch that also gets grounded via the metal dash support.

Thanks Guys... So Far I've Got The Grounds In Place...didn't Have Time To Put A Ground Ring On Headlight Yet...will Keep You Posted.bought A Used Harness ...maybe Thats All Or Part Of My Problem? Later.

Ok Guys Here It Is...all The Bulb Holders That Twist Into The Cluster Were Coroded . They Did Not Appear To Be However...soaked Them In Tarn-x Put Them Back In ...everything Lights Up. There Are Also Quite A Few Grounds That Do Not Show On Wiring Diagram.still Don't Have The Tach Or The Clock Working Yet.thanks For Your Help

I hard wire the dash instrument cluster in my 70. The printed circuit board was burnt up and I did not mant to purchase a new circuit board and have it burn up again. Anyway, when I got it all put together everything except for the gas gauge and the tach were working. I had to run a ground wire directly from the gauge cluster , metal backing, to the fire wall.