Adding Rear mounted CC fuel tank, sort of...

[stinson87]

So I have been searching for a while and cannot find much information on this, basically using the CC rear mounted tank circuits to control my auxiliary tank transfer into the truck.

Why? you can enable the dual tank option in Alfaobd and get a "factory" fuel gauge in dash. let the truck auto transfer when needed as designed from the factory.

**I will try to update this post as I go, and as information is gathered**

Known information:
C1/A pin 16 has the connector for the fuel transfer relay.
C5/E pin 17 connection for fuel level sensor tank 2
both need Kostal 32124734123000-L terminals

18awg wire needed for BCM to PDC (factory wire is pink)

BCM C1/A 16 runs to PDC C6 pin 16 and needs a Yazaki 7116-4780-02 terminal
PDC C6 pin 20 is output to transfer pump and needs a Yazaki 7116-4270-02 terminal

AlfaOBD:
VehConfig 3: Two Fuel Sending Units Present / "YES"
ECUConfig 4: Secondary Fuel Tank Capacity / "197 L/208 L"
CBC Config I/O: Fuel Transfer ON/OFF Relay Control - Pin A16 / "will update when verify"

Unknown information:
ohms of sender unit (Should be 0-90 ohm, will verify once I get wires installed.)


I don't care too much about correct DTE calculating off the two tanks, especially since factory is a 52 gallon tank, and my tank is over twice that. having a factory gauge without "pods" or other junk would be great.

 

[H3LZSN1P3R]

I like the idea… i have a 100 gal transport tank with sending unit that i wanted to have a level gauge but have been holding off as i dont want to add a pillar mount yet, if this works i may try that

 

[stinson87]

Pin 17 is the gauge level!
Now just to figure out what type of connector that is.

 

[H3LZSN1P3R]

@Jimmy07 any info/ knowledge we can borrow from you?

 

[stinson87]

So this is the larger connector in that harness: https://www.mouser.com/ProductDetail/KOSTAL/22140492060050-L?qs=e0jfwF9199%2BqIKWSgsY3Ww==
Wonder if it is from the same series of connectors? It is a pain to get into that connector, I installed my fog light harness just about blind but the smaller connectors are harder to reach. Ill probably have to remove more of the dash to reach these.

also,
from what I have been reading, the fuel sender has been 0-90 ohm since 2013? i was going to read my current tank but cant get to it very easy.

 

[Jimmy07]

Pin 17 is the gauge level!
Now just to figure out what type of connector that is.

So this is the larger connector in that harness: https://www.mouser.com/ProductDetail/KOSTAL/22140492060050-L?qs=e0jfwF9199%2BqIKWSgsY3Ww==
Wonder if it is from the same series of connectors? It is a pain to get into that connector, I installed my fog light harness just about blind but the smaller connectors are harder to reach. Ill probably have to remove more of the dash to reach these.

also,
from what I have been reading, the fuel sender has been 0-90 ohm since 2013? i was going to read my current tank but cant get to it very easy.

Pin 17 (the small terminals on all the BCM connectors) is Kostal 32124734123000-L

 

[stinson87]

Pin 17 (the small terminals on all the BCM connectors) is Kostal 32124734123000-L

awesome! ill get those on order! Thanks!

 

[H3LZSN1P3R]

awesome! ill get those on order! Thanks!

So the extra fuel gauge would be in the gauges you can scroll through on the 3.5” evic?

 

[stinson87]

apparently somewhere in the menu,

they explain the transfer here: https://www.cumminsforum.com/threads/dual-tank-operation-my-experience-so-far.2110905/

 

[H3LZSN1P3R]

apparently somewhere in the menu,

they explain the transfer here: https://www.cumminsforum.com/threads/dual-tank-operation-my-experience-so-far.2110905/

Thats a 4th gen with the big screen i wonder what the 4.5 gen 3.5” screen shows

 

[stinson87]

I'm trying to enable mine now. It just should just show an empty tank with nothing connected

 

[stinson87]

Yes!!! I am not sure how to choose which fuel gauge is actually on the mechanical gauge. But right now it shows my second tank on the actual gauge.

These are the two parameters I changed:

 

[H3LZSN1P3R]

Awesome!

 

[stinson87]

there is another option I am not sure if it needs enabled.

 

[Jimmy07]

there is another option I am not sure if it needs enabled. View attachment 23506

That one gets enabled. When the main tank gets down to 1/4, the BCM activates that circuit, which completes ground on the fuel transfer relay coil, which activates the secondary fuel pump to start transferring fuel into the main tank. Once the main tank is 7/8 full, it shuts off. If it isn’t already there, you’ll need to add this wire on BCM connector C1/A pin 16. That wire goes to PDC (fuse box) connector C6 pin 16, which is #86 on the fuel transfer relay. From there, you’ll run a wire from PDC connector C6 pin 20, which is #87 of the fuel transfer relay, to the aux fuel pump motor.

C1/A pin 17 connection for fuel level sensor

There’s no circuit on BCM connector C1/A pin 17, so I’m guessing you meant C5/E. Pin 17 on the C5/E connector is the main fuel level sensor, and pin 15 on the C5/E connector is fuel level sensor 2. In AlfaOBD, you’ll be looking to enable connector E pin 15 (or pin E15). I’m not seeing that in the list, so hopefully it’s already enabled.

 

[stinson87]

That one gets enabled. When the main tank gets down to 1/4, the BCM activates that circuit, which completes ground on the fuel transfer relay coil, which activates the secondary fuel pump to start transferring fuel into the main tank. Once the main tank is 7/8 full, it shuts off. If it isn’t already there, you’ll need to add this wire on BCM connector C1/A pin 16. That wire goes to PDC (fuse box) connector C6 pin 16, which is #86 on the fuel transfer relay. From there, you’ll run a wire from PDC connector C6 pin 20, which is #87 of the fuel transfer relay, to the aux fuel pump motor.

There’s no circuit on BCM connector C1/A pin 17, so I’m guessing you meant C5/E. Pin 17 on the C5/E connector is the main fuel level sensor, and pin 15 on the C5/E connector is fuel level sensor 2. In AlfaOBD, you’ll be looking to enable connector E pin 15 (or pin E15). I’m not seeing that in the list, so hopefully it’s already enabled.

My local mechanic at the dealership checked a 5500 chassis cab for the pin 17 in the C1/A whoever posted the picture I used of the BCM and it's package doesn't have a second tank.

But is the C5 pin connectors use the same smaller connectors as C1? It's not a problem for me to connect to either. Based off your experience in the group, I do trust your input a bit more.

I was planning on just running a wire to a relay and my pump, but I guess I could use the PDC.. interesting...

 

[Jimmy07]

My local mechanic at the dealership checked a 5500 chassis cab for the pin 17 in the C1/A whoever posted the picture I used of the BCM and it's package doesn't have a second tank.

But is the C5 pin connectors use the same smaller connectors as C1? It's not a problem for me to connect to either. Based off your experience in the group, I do trust your input a bit more.

I was planning on just running a wire to a relay and my pump, but I guess I could use the PDC.. interesting...

Of all the FCA vehicles that use this BCM, none of them use the C1/A pin 17 circuit.
Here’s the fuel delivery schematic. Based on it, I would use the circuits at the PDC relays, since it seems the PCM is also involved in monitoring that relay. https://drive.google.com/file/d/1OeHpmHrNjHAzZD4wRhH1p3C5vhvfRr5x/view?usp=drivesdk
The terminals are the same for the BCM C5/E connector.

 

[stinson87]

awesome! so, one last question... If I do not have N69 VT (pink wire, C1A[16] to PDC C6[16]) is the terminal on the PDC the same Kostal 32124734123000-L? Ill dig through the dash/PDC tonight to see if I can spot this wire, seems crazy to drop one wire from a harness but iv seen even more crazy actions from bean counters.

 

[Jimmy07]

awesome! so, one last question... If I do not have N69 VT (pink wire, C1A[16] to PDC C6[16]) is the terminal on the PDC the same Kostal 32124734123000-L? Ill dig through the dash/PDC tonight to see if I can spot this wire, seems crazy to drop one wire from a harness but iv seen even more crazy actions from bean counters.

The terminal for PDC C6 pin 16 is Yazaki 7116-4780-02.
The terminal for PDC C6 pin 20 is Yazaki 7116-4270-02.

 

[stinson87]

so a little bit of update:
Inspected the PDC and C6 16/20 are not populated (grey connector on PDC)

image from Jimmy07 - VSIM post.

The fuse is populated for the fuel transfer relay.

Ill order the terminals and continue the current fuel tank install.

for some reason I have the AUX PDC installed, with 3 relays in it. but can only find the blunt cut wires under the PDC that is found in the snow plow package? Ill have to dig in to that on another activity... Might be easier to install my aux switches!