FACM reset

[Tdci-Peter]

18 hours ago, Vadim G said:

I tried to connect another tank to the connector, but the errors appeared again.

This looks to be a problem with this piezo low level sensor again. As far as I can tell, the sensor is just a piezo-electric element (crystal) with wires connected, inside the tank. The FACM will energise this with some quite high frequency AC signal, and detect the change in capacitance or damping that happens when the level changes. So a failure can be in the tank, eg wire connections to the element, in the wiring or connectors, or in the FACM. There is no easy way to tell where the problem is.

Wiring in the loom can be tested by painstaking continuity tests from connector to connector, but intermittent problems are very easy to miss like this. Connector problems may be tested & partially cured by inspection for corrosion or dirt, and by cleaning and re-insertion. A LCR meter (as above) may be able to measure the capacitance of the element in the tank, though there are no truly reliable figures as to what it should be, Unfortunately the one figure that atanas (Jan 1 above) did not give was capacitance for sensor ok and tank full. The 20Mohm resistance may not be meaningful, could be just leakage currents,

Changing the FACM has, hopefully, eliminated that module, so the tank sensor becomes suspect no.1.

I would try various capacitors and resistors connected in place of the sensor element, to see if I could fool the FACM into seeing full tank. Easy for me since I have shed fulls of resistors and capacitors to play with! Maybe not so for others. I would start with 20Mohms, then 150pf, then various combos from there. It will probably be necessary to reset error codes, and maybe do a few ignition cycles, between each test.

[Vadim G]

11 hours ago, Tdci-Peter said:

There is no easy way to tell where the problem is.

Did I understand correctly, from the correspondence above, that if you disconnect the connector on the tank, then the P1922 error should disappear and a network failure error should appear? And this will mean that the FACM unit and the wiring to the tank are working properly, but the problem is in the tank itself and in its sensor?

[Tdci-Peter]

2 hours ago, Vadim G said:

if you disconnect the connector on the tank, then the P1922 error should disappear and a network failure error should appear? And this will mean that the FACM unit and the wiring to the tank are working properly, but the problem is in the tank itself and in its sensor?

I doubt if is like that. There is no real difference between a sensor failing by becoming open circuit, and disconnecting the connector, so it is not likely to change the error code. I would have thought a network failure (typically a U code) would be for a fault in the comms or processor part of the FACM, or in the CAN bus from FACM to ECU.

I was suggesting using the information that atanas posted on Jan 1 to attempt to find something that behaves like a sensor in a full tank. He said that an ok sensor in an empty tank measured about 1000pf, but seemed to have problems getting a reading with the full tank. My guess would be a lower capacitance, with a series resistor of a few kohm to simulate the damping effect of the fluid.

[fryc88]

Hi.
Is there any progress here with 1922 code?
I have changed additive tank, replaced module but 1922 code always comes back, no matter what i do. Sometimes its off for few days, but then it's back on again.
Also, in my 'new' FACM firmware version seems to be very very old comparing to car year model, and my original it was newer i belive (i lost it so i can't double check it now). Is there any bin available to program it?

[xpto2000]

On 1/1/2021 at 12:35 PM, a.tanas said:

Hi!

The thread was very helpful and I just have repaired FACM tank after buying one (second-hand) and it was fitted in replacement of the original failed one. It failed after 250k km (150k miles) on Mazda 3 1.6 diesel, which you probably know is mostly Ford Focus in terms of engine systems.

I'd like to contribute with my measurement (with GM328 tester of Aliexpress) of the failed and the OK tank:

Measuring at the tank connector:

- the pump measures like a coil with resistance about 9 Ohm and inductance 5.1 mH.

- the piezo sensor, if failed, is open circuit while tank empty.

- the piezo sensor, if OK and tank empty, measures capacitance 975 pF.

 

Measuring at the FACM cable loom connector:

- the piezo sensor, if OK and additive filled, measures resistance about 20 MOhm.

- the piezo sensor, if failed and additive filled, measures resistance about 150 pF (effectively this is cable loom's capacitance).

 

One useful observation: While you have the MIL light On at the dashboard, the system still tries to add whatever available in the tank. It's worth to continue driving with the FACM installed on the car to avoid quick clogging of the DPF. I soldered a 12 V buzzer in parallel to the pump pins inside the FACM black box. This way when 12 V are being fed to the the pump the buzzer rings.

After filling fuel at the petrol station I departed and after 2 mins of driving I heard as series of pulses (much like a ringing phone for 2-3 secs) which is equal to some 50-100 pulses to the coil, ejecting droplets to the tank.

 

there is the anser to tric the FACM module.

You just have to put e resistor of 20Mhom between the pins number 4 and number 2  of the FACM tank and it whill trik the FACM to think thath there is eolys in the tank.

Problem solved.

i'm going to try tomorow then i post if it Works .

 

[xpto2000]

1 minute ago, xpto2000 said:

there is the anser to tric the FACM module.

You just have to put e resistor of 20Mhom between the pins number 4 and number 2  of the FACM tank and it whill trik the FACM to think thath there is eolys in the tank.

Problem solved.

i'm going to try tomorow then i post if it Works .

 

if instead you decide to put the resistor in the FACM module it wil be between pin number11, and pin number 10.

[Juraj700]

XPTO2000

..So did you trick the FACM module?  I have got the same problem

[fryc88]

That method didnt work for me

[donalddcn]

On 10/12/2022 at 8:51 AM, fryc88 said:

That method didnt work for me

try this. 

https://www.motor-talk.de/forum/additivtank-fehlermeldung-erscheint-nach-nur-9-000-km-wieder-und-laesst-sich-nicht-loeschen-t6500433.html?page=5#post62736154

[boycie100]

Thank you Donalddcn ! I've had the P1922 issue with associated P2585/Engine Systems fault/powertrain control lamp on. But not any more! Aso thanks to our German friends on the link supplied. When translated to English someone there said the real issue is with the FACM - a chip within it no longer supplying 5V to the piezo sensor in the FA tank. Someone else then said the fix is to first cut the wire from FACM pin 11 and tape off the half going to the FA tank, then second connect the remaining half of the severed wire to FACM pin 7 (thus pin 11 and pin 7 bridged).

I don't really like cutting loom wires so I did something similar to the above by just adding a bridge wire between pins 7 and 11 without cutting wire FACM pin 11 to FA tank, and it still worked! So this is a pure bridge between FACM pins 7 and 11.  

I have no idea WHY this fix works or what it actually does, all I know is that it does work.

So now no need to purchase new FA tank or FACM from Ford at rip off prices, or even a second hand which may still not work.

I don't know if the dosing system will actually work correctly so I will manually dose the fuel tank myself with a few mls of JML additive after each fill up. I've was doing this already as I know my fuel filler cap switch was faulty and didn't want to pay over £40 for a new one.

Good luck