I have been able to get a few things done on the truck in the evenings this week. I have been working by flashlight on it, but making progress.
I got my connectors in that I needed and made up the 6 wires {Tach, Speedo (VSS), TCC, Tow Haul, Serial Data, MIL control} from the PCM that go into the interior. I used the grommet and hole that the old mechanical speedo drive cable came thru the firewall as my point of entry to the interior for those 6 wires. I have installed the new NC/NO brake switch and got the wires connected to that switch under the dash. I re-pinned the instrument cluster for the 1990 Suburban Electric Speedo IC and got that installed. That included the 2 wires from the PCM for the MIL light control and the Speedo. All I have left for the wiring on the PCM is the Tach (whick I have not decided on what tach to get and use or even have one at all), the Serial Data to the ADL connector, and the wire for Tow Haul mode. For now, I will leave the Tow Haul and Tach wires long and cap them off till I decide what I want to do with them.
Here is the new IC installed in the dash. the WHITE wire to the right of the IC is the Tach wire...
Here are the TCC wire (purple), the Tow Haul (orange), and the Serial Data (green) wires. I have already done the TCC wire after I took this pic.
I also need to run a 12v+ Key On wire into the engine compartment to the PCM. In the Engine bay I need to run new wires from the bulkhead connector of the factory harness for the Oil Pressue and the Water Temperature senders on the engine. I also need to finish the routing and install the power wires and starter wires from the bulkhead to the starter and the power distribution block on the firewall. I will use the stock '85 ground cable for the Battery and the stock 2000 model power cable from the battery to the starter. I hope to have the all the electrical finished and tested by the end of this weekend.