2017 Ford E450 Cutaway RV with U210B

I have the U210B on this vehicle and have tested the ENS circuit. With the RCM unplugged, KOEO I have no voltage at the ENS wire at the RCM connector. I verified wiring integrity on the ENS wire from the FPCM to the RCM. As per the Ford Pinpoint tests I replaced the RCm with a Ford Module and I still get not output on the ENS. I have checked for voltage at the FPCM ENS wire and nothing. I do show around 40 ohms between ENS and ground at the RCM connector. This changes based on the condition of the key. What is the internal logic of the FPCM to output the voltage for the RCM to pull down to the 40% duty cycle?

Thanks,
Scott

Forgot to mention this is a V10.

The customer complaint is very rarely the fuel pump does not come on with the key. I have tried to replicate the fault but have not been able to.

Hey Scott! Welcome to the forums.

I'm following along with your testing and pulled up the Ford pinpoint testing for U210B, which directs me to the KC pinpoint tree. You've already tested the ENS wire integrity, so I skipped KC30-34 and got to KC35:

 

No voltage at the ENS circuit with the FPCM plugged in, RCM disconnected and the key on, right? That would indicate a failed FPCM. Did I miss a step? Or, did I misread your testing?

Has the FPCM been replaced previously?

What is the internal logic of the FPCM to output the voltage for the RCM to pull down to the 40% duty cycle?

I'm not sure what the internal logic of the FPCM is? I haven't seen an FPCM equipped with the ENS circuit that didn't put out a steady voltage on the ENS circuit. Not to be nitpicky, but it's not actually the RCM that pulls anything down to 40%. The 40% is on the Fuel Pump Monitor circuit from the FPCM to the PCM. The PCM supplies a signal voltage on the FPM circuit and the FPCM varies the duty cycle. 40% is the specified pulse width for 'something is wrong the RCM/ENS'.

Yes those are the test conditions. I have replaced the module with two Dorman units and a OEM. All do the exact same thing.

So the PCM is part of the ENS circuit? I didn’t see the ENS circuit going to the PCM in the diagrams. The way the circuit operation read in Solera it made me believe that the FPCM produces the voltage. Then the RCM pulls it to ground to generate the duty cycle. I imagine then there is a comparator in the RCM that looks to see if the duty cycle on the ENS is correct, or incorrect. From what I understand it’s a pass or a fail.

Would it then test the circuit to inject 12vdc at the ENS wire on the FPCM and then test what the RCM does with it? That would tell me if the RCM is good. But still I can figure out why the FPCM is not producing the voltage.

   

In this diagram this shows the wire going to the Electronic Engine Control. Is this the wire that goes to the PCM? Is there another device on this circuit that could be pulling it to ground?