Factory gauge cluster

[Tiggie]

I'm digging into my own similar problem. There is an orange/white wire in one of the connectors that is a ground for the speedo that might be worth checking into.

Here's the diagnostics for a 1994.
https://charm.li/Ford/1994/Crown%20V...%20Inspection/

And the cluster for a 1991. https://charm.li/Ford/1991/Crown%20V...ent%20Cluster/

[Kodachrome Wolf]

As I recall, '90-'91, '92, and '93-'94 share some similar pins, and different in others, especially in consideration to warning lights. Played around a bit with that sweeper cluster I had in my old '97.

I specifically recall the '90-'91 Box era steppers liked to stick in the speedometer heads I had, and got worse when the backlights were on and warmed the insides of the housing. Most reliable setup I had used a '94 Marquis stepper motor on my Box 140 cluster. Had to swap the circuit boards via desoldering and soldering since the speed logic was different between them. After that repair, the cluster worked a treat right until I sold the car.