It sure looks like the schematic for the precharge board is done. I see something that does not make sense yet it matches the original board perfectly. It was a fair amount of work. But I’ve noticed that the #2 truck has a hard time booting up sometimes. I think the 24k miles on it has worn out the precharge relay. The #1 truck is on it’s second precharge relay. Commuting with the #1 truck will surely wear out it’s second precharge relay, quickly too.

At some point I need to get a board made and start testing it before the precharge relay goes out completely on the #2 truck. I may also make a 2nd board layout that is exactly the same as the original board. Right now the components are in the same place but the traces are routed differently. At least I did find all of the data sheets for the parts. The capacitors were the toughest to find by far. I do need to open a Dolphin and look at those two tapped holes on the Dolphin floor to see if they match up to the holes in the original precharge board. That would be nice if all Dolphins were tapped to mount a precharge board!!