I have a 1966 mustang with a straight 6. I took apart my dash a few weeks ago, and noticed later that the fuel, oil pressure, and temp. gauges were not working properly. As soon as I start the car, the fuel gauge goes all the way past FULL, and stays there, I do not have a full tank... The oil pressure does the same on start up. After driving for a few minutes I notice the temp gauge goes up past H as well. I took the gauge cluster apart this weekend, thinking I mistakenly unhooked some wires, but all were connected properly. I checked to see what else could be the problem but all I came up with was the Constant Voltage Regulator. I went to checker and autozone to see if they carried one, they do not. Anyone have any ideas, or know where I can find a CVR.?
Any help is greatly appreciated.

 

National Parts Depot has them! you sure you did not connect the wires backwards? or someting is incorrectly grounded

 

I don't think there are any NPD, here in Tucson. I looked at the wiring diagram for the gauges everything seems correct.

 

Some how you have done something the change the voltage to your gages. You're routing 12V to your gages rather than the 5V from the CVU. So either you've bypassed the CVU (got the wiring crossed) or you've toasted the CVU and it's now a dead short. You can test your CVU with a Volt meter and a couple of wires. The incoming lead to +, the case to -, and the output lead should modulate 5V. Hook your DVM to the same ground and to the output lead.

Email Laurie Slawson at aztlan@theriver.com . She is a local in Tucson and a national director for Mustang Club of America. I'm sure she can tell you where in Tucson to find any vintage mustang part there is.

Look at the info below, then go back and check your wiring....to see if you didn't cross something when hooking it back up.

 

So I check the CVU, it was bad, I bought a replacement. I installed it, and now it seems that the Temp. and Oil Pressure might be working. But the Fuel Guage starts to go up gets to the quarter tank line then goes back to empty. I filled up today, so I know there is a full tank in there. Ideas Anyone?