My 72 Imperial was running fine before we pulled the instrument panel. When the panel was out the engine would die when the key was released. I've reinstalled the dash and the engine still dies when the key is released.

Andrewh and I pulled the cluster to clean it and get the fuel gauge working. He found some random wire under the hood that was dangling and not plugged into the bulkhead connector. Naturally, he plugged it back in. He used the wiring diagrams to locate it's proper place.
He also fiddled with the ballast resistor but I made sure it was plugged in.

Is there anything related to the instrument panel that would cause this problem?
The steering column was not unplugged and I tried to reconnect all the ground wires.

Did you try swapping out the ballast resistor? That happened to me before and changing it fixed it. Even though it 'looked' good.

The ballast resistor would be the first thing I'd look at. This one is less than a year old. The kicker is that it worked before we removed the instrument cluster a couple weeks ago.
I was just going over the wiring diagrams and didn't see any obvious culprits but I don't know which wire in the bulkhead Andy messed with.

I think I've got a spare ballast resistor and I was about to try it.

The ballast resistor tested the same as the new part I had. I swapped the resistors and it still died when I released the key.

Feets there are tow wires that feed the igntion one is hot with the key in the start postion and the other is hot in run. In the wiring diagram I believe they are called ign1 and ign2 at the ignition switch. SWee what color they are and trace them through the bulkhead conector. The one on the start side bypasses the ballast and the other feeds the ballast power. You need to ask Andrewh what wire he worked on.

I called him but the wifegod intercepted. Andy is babyfied and unable to talk. Perhaps he'll call me tomorrow.

The good news is that the fuel gauge seems to work. Kinda. I've got about 3/4 tank and the gauge reads a touch under 1/2.

I'll have to check the wires for voltage in the morning. We're supposed to get ugly storms so it may have to wait until later in the day.

Yep, what Stumpy said.

I'd disconnect the line to the starter, then use a DMM on ign1 and ign2 at the ballast while playing with the key to see which voltage isn't there when it should be.

Then it's just tracing it back to find the break, which could even be the ignition switch itself.

Most likely the dark blue wire at the bulkhead feeding the balast resister.

Test light each wire sets that attach to the ballast first. Disconnect them from the ballast before testing.

The one on the coil side should be hot in start, other side in run. Neither should be hot in both key positions.

Got power in both sets, look at the ballast. If not, look at the bulkhead next.

pretty sure it is 27 in the bulkhead connector.

but that did not have anything to do with ignition.

looks like there is some big splice for power with key on.

looks like it should be down in that goo under the fuse box. did you pull it apart to get that relay out?

Look at the big connector on the column also.72 thru I believe 75s had a problem with them getting hot and losing contact.My 73 would lose power.I pulled the connector apart cleaned it and replaced 2 pins and had no problems after that.Rocky

try changing the ECU.