Originally Posted by Squishy!
Sensor unplugged ignition on. Looks like the wiring or cluster. I've got a spare cluster so we'll start with that. Also. My DMM is missing
Whenever Harbor Freight or MCM Electronics has a sale on cheapies I stock up, put one in each vehicle, plus several around the house and garage. For under ten bucks who cares if they get lost or run over? They aren't expected to be super-accurate but as long as you have an extra in case a reading doesn't pass the sanity check you can always cross check with another.
As for your root-cause, I put my money on a wire rubbed through and shorting to ground, typically where it goes through a bulkhead or maybe melted somewhere.