Intermittent Gauges

• 1968 gauge cluster
• Replaced the Instrument Voltage Regulator (IVR)
• Gauges go on and off while driving.

A month ago all my gauges died so I assumed it was the IVR. I ordered and replaced that part and during my test drive everything seemed fine. I drove the car the next day and after about twenty minutes the gauges went dead again, then they started working, then they died, then they worked. You get the idea.

It sounds like a loose ground so I plan to take the cluster out and physically check the connections but since it is intermittent I do not expect putting a meter on it will be definitive.

Any other ideas on what it could be?

Update

I took the instrument cluster out and with the harness still pligged in I hooked the battery back up. I get a clean 12v coming to the IVR. I checked the output from the IVR and it cycles to 10v about every 10 seconds. From what I ready this is not right.

I plan to order the electronic voltage regulator from The Paddock. I now I could build my own but just do not trust my skills to get it right.

While I was there I verified the ground on the back of the cluster is excellent and the connection from the IVR out to the gauges are solid.

The wires surprisingly looked good and I see no bare wires after 40+ years. One huge benefit for me is my parents are the original owners so I have been working on this car since I was a kid.