instrument cluster voltage regulator

Hello, I am having a big problem with my voltage regulator on my 65 mustang coupe, I have tried 2 new ones and both act the same, I get a reading of 12v coming in, but coming out it also reads 12v for a second then it goes down and up,it is not reducing the voltage down to 5v, my fuel gauge and temp gauge both go to max ass soon as I Turn the ingnition on. Can any one help?
thanks,  

icvrs have 3 leads...   12 volts input..   ground....    regulated output.. actually not really regulated .. but pulsed output..

enough to keep the gauges up...

there are ways to open them and install a real electronic voltage regulator..

but i would like you to properly check the ground side of the circuit..



so it actually averages the voltage to the gauges...     _-_-_-_-_-_-_-_-_   is what it is supposed to do.. if the ground is bad.. or the load is wrong..   ...


can you measure the resistance at the sending units..   make sure that you don't have temp switches.. and oil pressure switches..


i have forgotten... what happens when you hook up the system with the sending units disconnected...

they will usually swing one way.. ground them.. they swing the other way..     test for resistance at the gauge wires at the dash board...   should be the same...

oh.... and how is the ground between the battery and the engine block...   the battery and the body....    and ....  the engine block and the body..



oh.... and you think that i don't know what i am talking about..    the case mounting tab is the ground... on some...



by the way... how does the cluster ground on a 65??????  

sounds like a weak cluster ground to me as well. if you have to run a large gauge (8-14) ground wire from the IR mount screw to the bracket behind the panel. jlg  

Ground wire cure the problem, thanks for the advice.