The Hanes manual was a lot less useful for the how-to on removing the instrument cluster than I would have thought. It gives diagrams on the circuit, but no pictures on where the screws are, or what each pin is for on the connector.
This guy, however, does a GOOD job showing how to remove the instrument cluster, and a table of what each pin does for the digital cluster as well as the analog cluster.
Instrument Cluster Conversion
Following his instructions I removed the environmental controls, the switches, the various screws on the bottom of the dash, then the digital instrument cluster.
I took the instrument cluster to my basement, then connected 12.5V from a gel-cell battery between 21 (B4) and 24 (B7). There was no response from the cluster. No display at all, just like it was inside the truck.
I re-read the descriptions and decided to try looking at the connector from the other direction, using 21, Battery +12, at B28 and 24, ground, at b31. The result was the same.
Many vehicle connectors are setup up so that if you connect power or signal backward (like looking at the pinout from the back instead of the front) that there will be no damage. Not sure if this is the case or if it was already dead and there was no more damage to do.
This ends my investigation into the digital dash for a while. A used display from the local wrecker is about $120. I guess I'll invest that cash when I'm closer to getting the thing rolling.
No news from the neighbor who agreed to pull the engine and transmission. He was going to have some time last week, which pushed up my schedule for checking things out on the dash to see what voltages were required. I still don't know the voltages and I guess I won't until I buy a replacement.
I should call him and see how booked up he is.
As for some of Jeff's questions, I have not checked. It has been raining or drizzling for a couple of days and I am too lazy to stand in the rain to connect up the battery so that I can check for power on the connector in the dash of the truck. I have no loose pins for that connector, so I'd be using a paper clip or something like that. I'd hate to damage the connector in the truck with my clumsy testing.