Landing lights make gauges go bad, help!

I have a new to me RV9a. Went up for a night flight today, first time flying it at night.
And after my first landing: oil pressure pegged high, alternator voltage low, fuel pressure read zero. Turn off landing lights, slowly come back to normal.

I’m guessing I have a bad ground. Took the engine cowl off, and have been tracing wires. Nothing obvious.

Anyone run into this?

Frustrated.

Seems it is related to excessive current draw of landing lights, Strobe, radio, etc.
Lights weren’t dim so think the alternator output is fine.

Any help greatly appreciated.

I would check the grounds to the landing lights, consider a dedicated ground for them. Also check for a real ground from the engine to the firewall, or better yet, to the negative battery post. Don’t rely on the engine mount to grounding through the mounting bolts. Can you duplicate the problem on the ground.

Yes, can duplicate on the ground, with engine off or on. If I turn on landing lights, nav lights, strobe, my fuel pressure, oil temp gauge go south. Fuel pressure reads 0, oil temp reads max. Turn off landing lights, they normalize.

Didn't build the plane, so playing catch up and the "what was he thinking" game.