all gauges Inop in my 70 mach 1

Just fired up my 70 Mach 1 for the first time only to find out none of the gauges work. (no tach). I tried grounding the oil and water sending units wire at the engine. I was told this should give you a max reading at the Gauge. (power on). Nothing. I pulled the Gauge cluster voltage regulator off the back of the gauges and tested it. 12vdc input and got a pulsing 6 to 8 vdc output. Looks good. Where to next? I love this stuff.  

ground....   where is the cluster grounded to ????/   how is it grounded.. one of the leads from the instrument cluster voltage regulator is grounded...    follow that trace..  find the wire..

i will take a look at the diagram of the dash circuit board if i have it... and come back.. and edit if there is anything to add..


the second trace up from the bottom is the ground circuit...   looking at the back of the cluster... where the wires plug in..

the right side of the connector  looking at it from the back with it plugged in...  not the bottom right terminal.. it skips one.. so the third position up on the right... above the only skipped connector is the ground wire for the entire dash..

the ground wire for the cluster looks to be a black wire.. and is also connected to the clock light bulb socket.. but both are grounded somewhere...

hope this helps...  

Thanks, As far as grounded I assume it's grounded when it's screwed into the metel dash. Hmm I didn't have it grounded when I was troubleshooting it. I had it pulled out as far as the wiring harness would allow. I will makw a jumper with clips to keep it grounded.
I noticed that one of the connections from the regulator was grounded.(via meter). I thought this was the problem, guess not. I will follow your input tonight and see what gives. Thanks  

I love those little bugs. I am tring to find out how many 1970 mach 1 were built in hugger orange with a shaker and a four speed with a white interior.  

Look here:

http://1970mgr.org/_GaugesQuit.htm

Each gauge in your cluster, except the speedometer and tachometer if equipped, should be installed so that the two posts on the back of each gauge are centered in the rectangular opening in the metal housing. The brass nuts holding the gauges in place are meant to hold them centered and connect them to the printed circuit board. If the cluster has been apart and the gauges were not installed properly, sometimes the gauges can shift in their opening. If the hot post of a gauge touches the metal housing, it will cause that gauge or others to stop working.  
Bill Hamilton

My 1970 Mach
1970 Mach 1
2003 Mach 1

unless the guages are different from a 65.  if all the guages are not working it is one of two problems.  either the power wire going to the cluster or the voltage regulator.  as these guages work by modulating the ground. through the sending units.  power goes from the fuse box to the icvr then splits to each guage then out to the sending unit which modulates how much power is grounded to get the reading.  so if all the guages are not working it is the power getting to the guages where you are having issues.  here is a link to a good write up on gauges.  it is geared to 65 66 mustangs but it should be similar to yours.   it is about 2/3 of the way down the page.  


http://thecareandfeedingofponies.blogspot.com/search?updated-min=2008-01-01T00%3A00%3A00-08%3A00&updated-max=2009-01-01T00%3A00%3A00-08%3A00&max-results=32