Mid ship fuel tank

[Big Baloo]

I have a 90 gallon AUX tank in the bed of my truck.
I am not really interested in the auto-transfer of fuel. I already have it connected to transfer via one of my aux switches. (electric solenoid and pump turns on when I activate the aux switch)

Is there a way to just hook up a sending unit to read in the gauge cluster?

 

[commoditie]

That sounds mostly right to me, although I am not sure about pin 29 being right for the PDC output for the transfer pump. On my truck that was connector C6 pin 20, but again mine is a 2022 chassis cab and a 2019 HD may be different.

Those 3 settings need to be changed, but you are missing a big one - you need to connect to the engine computer (totally different module when initially connecting with AlfaOBD - usually you connect to the body computer for those 3 settings) and then set:

Dual Fuel Tank Enable/Disable: Enabled

Otherwise you'll never get it to trigger the transfer pump.

I'll attach the wiring diagram PDF I used (which again, is for a 2022 4500 chassis cab, not a 2019 2500) in case it is useful. You need to line the pages up left to right to follow it all.

Hope it works out for you and I hope you'll let us know how it goes, the other guy who tried this in the other thread never reported back.

Hey Gprguy, you are correct with the C6 pin 20. I inadvertently typed pin 29 by mistake. Thank you very much for the PDF's that is very helpful. So I got under the BCM again to confirm the colors with the PDF. Again, I have a 2019 RAM, so not sure what changes, but C6 pin 20 is blue with a yellow tracer, but C6 pin 16 is not pink but purple. I have attached some pics to confirm what I am verifying. Not sure where to go from here, as I have the wiring ready to tap to the aux sensor and fuel pump. FYI I also set AlfaOBD from the engine computer to "enable" the dual fuel tank, so thank you as well for that!

 

[gprguy]

No problem glad that helped. For C6 pin 16 the PDF shows it as pink to my eyes, but the code on the drawing shows as VT (Violet). Confusing I know, but that sounds like the right wire to me.

Hope that gets you across the finish line.

 

[gprguy]

I have a 90 gallon AUX tank in the bed of my truck.
I am not really interested in the auto-transfer of fuel. I already have it connected to transfer via one of my aux switches. (electric solenoid and pump turns on when I activate the aux switch)

Is there a way to just hook up a sending unit to read in the gauge cluster?

If you can find a sending unit that mimics the output of the factory ones (I know I posted the ranges earlier in this thread somewhere, but I can't find it right now) then possibly. I would guess that you would only need to set:

VehConfig 3: Two Fuel Sending Units Present: Yes

ECUConfig 4: Secondary Fuel Tank Capacity: 197 L/208 L

That said, I don't know what it will due to your DTE (it'll be wrong for sure) and I don't know if it'll throw codes. I don't know that anyone has tried this and reported back.

You'd also have to tap into the secondary tank sending/return wires forward of the XY965A connector (the blue one) since those wires won't exist in the rear half of the harness.