Spoofing the ENS signal (From the RCM) to the FPCM in a newer Ford return-less fuel system?

[Chuck W]

I'm working on a swap project using a 2011 Ford 3.7 and wanting to try and keep the return-less fuel system (Along with most of the other emissions systems).

The swap involves a stock ECM, but there is no RCM (Restraints Control Module) in the car, as it is built in the 80's.

Digging through wiring, the FPCM gets an input from the RCM (ENS), basically informing of the status of the vehicle. It's meant to disable the fuel pump in the event of a crash, or some other incident (similar to the inertia switch).

Lots of searching online for a solution, don't really get into what the signal is, and the Ford swap kits with the control packs just switch to a return-type fuel system. Some of the other swaps are into cars that have an RCM in them and just require wire splicing, etc., which is not applicable here.

Then I found the old Ford patent application for the system HERE(and attached), and it kind of fills in the missing info of what that ENS signal is.

The signal is a fixed 10Hz frequency signal. When an issue occurs, the frequency changes and the system reacts accordingly.

Other info I found is that the FPCM monitors the ENS signal by sending a 12V(batt) signal on the ENS circuit to the RCM, meaning to me that the RCM pulls the signal to ground.

My thought is to use a basic frequency signal generator like THIS GUY.
Since the FPCM sends voltage to the RCM, I wouldn't want to connect the PWM(power) side to the FPCM, but instead just connect it to the ground. My thought is that would cycle the frequency of the applied signal.

Am I thinking about this correctly? I know there are a lot of very knowledgeable folks here, especially with electronics experience. If this won't work, are there any other suggestions for producing this signal?
I can switch to a return-type system, but really don't want to if I don't have to.

The car will be retaining an inertia switch to cut fuel delivery in case of an accident/collision.

Any thoughts or input would be great.
Thanks!

 

[bobxyz]

I'll take a look later this weekend. I did get a good laugh from the inventor on the patent - Mr. Tippy

 

[bobxyz]

It's certainly worth trying with that pulse generator. You'll need to add a transistor/resistor so that it only drives low. You might also need a pushbutton switch so that there's a delay before the 10Hz pulses start. It wasn't clear from the patent, or web posts, how long the delay needs to be. If you have access to a working TPDM and an oscilloscope, it would help to measure the initial key on to pulses starting waveforms, and to confirm that 10Hz is the actual frequency. (Note: the 2N3904 is a generic NPN transistor, others are fine. The pushbutton should be normally closed, not the normally opened shown below.)



Additional info from a u210b OBD code post:

2010 Expedition u210b Fixed

2010 Expedition u210b Fixed

www.scannerdanner.com

 

[Chuck W]

Thanks for that! I may even have some of those transistors on hand.

I'll be able to test it out when I have more of the wiring together.