Also, I have received a few offline questions, so I want to reiterate conceptually how all this works:
- This is a completely stand-alone subsystem as it is installed from the factory. US trucks have ALMOST all of the wiring in the back, but not all. The truck does NOT have the ECU or the subharness that connects from the side truck harness over to the transfer pump and main tank float switch. The truck DOES have connections for both. The truck DOES NOT have the wiring up front to control or power the system. That must be added by you as those connections do not exist.
If you had all the parts available, here is what I would suggest as an installation sequence:
1. Disconnect the battery and using the FSM, disconnect the main fuel pump from its connection under the driver's side passenger door. Drain the main tank. Drop the main tank and have it modded to accept the non-US float switch. I have a local machine shop with a CNC program for this steel ring and they can cut it the correct size and its already drilled and tapped to receive the float switch. All you do is have a local tank shop cut a hole and weld on the ring. Email me offline if you want to buy one, they are $100 shipped. Note>> I would NOT suggest cutting the hole and just mounting the float to the tank, it'll never seal without a reinforcing bung ring to screw into.
2. Remove the existing main tank fuel pump bracket and move your pump and pickup parts over to the non-USA bracket that has the extra supply line plumbed in. Reinstall the new bracket with a new filter sock and gasket. Attach 3-4 feet of fuel line to the subtank supply port. Attach the other plumbing for the main tank and connect the subharness to the new main tank float and route it towards the driver's side rear. Reinstall the main tank.
3. Install the transfer pump/solenoid assembly and connect the fuel lines from the main tank. Plug in the appropriate subharness connections. Now route the remainder of the subharness up over the frame and to the side sill connection under the driver' side passenger door. Plug it in and secure it to your liking. Also plug in the main pump you unplugged earlier.
4. Install the dual filler neck, subtank and fill hoses. You'll have to cut and modify the main tank fill pipe as discussed in other sutbank install threads. You'll also have to cut holes in the metal floor ribs for the mounting strap rivnuts. Once the tank and hoses/filler neck is mounted, then attach the subtank sender to the existing rear harness connection. The rear system is now done.
5. Mount your overhead console and run the wiring down to the kickpanel.
6. Remove driver's side kickpanel. Using the diagrams in this thread the rear system needs power from the fusebox, ground, switching from the dash switch and an interface to the DLC diagnostic connector. Optional is the overhead console wiring. Following earlier instructions pull all the necessary subtank wires out of the 4 existing connectors in the driver's kickpanel and group them into a new connector. You now have every wire you need to complete the system and each of these wires must be fed by a new wire that you will need to run.
7. Using the earlier posted master diagram, create feeds to that new group of wires. These feeds come from fusebox power, the DLC, the dash switch and the overhead console . You have to run new wires to the dash switch (which consists of illumination and grounds from the dash rheostat and two of the pink wires from the subtank circuit.) You also have to run 12V+ from the fusebox and a ground for both the subtank system AND the overhead console. Lastly is the DLC input, which is a matter of splicing the black/blue wire from the rear harness into the black/yellow wire in the kickpanel ECU. (see pic below)
Once this is all done, you are ready to test the system and install the subtank ECU. There are docs in my original post that show you how to diagnose this entire circuit before ever plugging in the ECU. I hope this helps.