I have a 1970 Mach 1. This is the second post but the first post didn't fix the problem. I installed LED's in my instrument cluster. When I got done everything worked except the Fuel, oil and Temp gauges. The gauges worked fine before installing the LED's. First thought was the IVR. Bought a new one. Gauges still didn't work after installation. I am sure the IVR is good because when I put 12v to the ignition side of it and ground the body I get a good pulsing out of the remaining terminal. I checked the plug that goes to the back of the instrument cluster. All the appropriate terminals are either getting power or are grounding out. The gauge cluster is properly grounded also. I took the LED's out to see if that was the problem but no still no gauges. Everything else works (turn signals, highbeam indicator and dash lights). I was wondering if I could have fried anything while poking around with the test light. What are my next options? I really don't think all three senders fried at once. Could the gauges themselves fry out somehow? If so how do I test those? I had to fry somthing that Iv'e been over looking. This is really getting to me as I have had the gauge cluster out like fifty million times already. I'm at my wits end over this problem that shouldn't be that difficult. Thanks in advance to all that respond.