Test Duramax CFF "Change Fuel Filter" sensor?

[D60]

I'm facing an LML that likes to tell you to change the fuel filter much too often.

I'll look for the kinked hose, algae etc, but I'd like to know test procedure for the CFF sensor GM 12641590

It looks to be a 2-wire sensor so can't be that complicated, but I don't know if it's a VREF or a simple on/off switch, and how much vacuum I'd need to apply to trigger it

Additionally, not sure if I can see this on live data in an upper end scanner. Have not had time to see if it shows.

@clinebarger

 

[clinebarger]

The fuel filter pressure switch is a normally closed switch located next to the fuel conditioning module. If fuel supply line vacuum reaches greater than 14 in Hg the switch will open. The engine control module (ECM) monitors the voltage on the fuel filter pressure switch signal circuit and will send a serial data message to the instrument panel cluster to display the FUEL FILTER RESTRICTED message.

 

[D60]

The fuel filter pressure switch is a normally closed switch located next to the fuel conditioning module. If fuel supply line vacuum reaches greater than 14 in Hg the switch will open. The engine control module (ECM) monitors the voltage on the fuel filter pressure switch signal circuit and will send a serial data message to the instrument panel cluster to display the FUEL FILTER RESTRICTED message.

Man this was so helpful, thank you! I got the sensor out with minimal difficulty and was able to bench test. At 14-15hg it reliably opens the circuit.

So, parts cannon avoided and on to look for other causes!

 

[BrianF]

Is this one of the models without a lift pump (presumably since there is the manual pump on the filter head)?

So i am wondering if there is actually a physical obstruction some where. Maybe a rubbie living in the fuel tank, causing the in tank strainer to clog, or tha actual fuel filter to clog?

 

[BrianF]

Have you physically inspected a filter for material?

 

[D60]

Is this one of the models without a lift pump (presumably since there is the manual pump on the filter head)?

So i am wondering if there is actually a physical obstruction some where. Maybe a rubbie living in the fuel tank, causing the in tank strainer to clog, or tha actual fuel filter to clog?

Eh these are kinda notorious for this problem. It could really be bad fuel or algae, or I've read of a cracked pickup "straw" in the tank, or collapsing fuel lines in a couple different places. There's also the fuel rail "pop off" valve that gets weak and dumps fuel pressure when it shouldn't, but in the past I've received codes like 0087 with that.

There are other potential culprits I'm forgetting but I'm glad to have tested the CFF switch. The CFF switch didn't debut until the LML and I don't think it lasted much past 2016? Maybe?....would need to brush up on my research

 

[clinebarger]

I would expect a P0087 if the system was actually restricted, keep in mind any intermittent open between the sensor ground & the ECM will trip the change filter message.

I recommend installing a lift pump on all Duramax trucks like a FASS or Airdog.

 

[D60]

I would expect a P0087 if the system was actually restricted, keep in mind any intermittent open between the sensor ground & the ECM will trip the change filter message.

I recommend installing a lift pump on all Duramax trucks like a FASS or Airdog.

Thank you! On my non-profit's LMM I installed whatever Kennedy was offering. After a couple years the control relay (little black box with the red light) locked on and started draining the battery. I think it was running the pump 100% of the time but those centrifugals are so quiet you never know.

I verified the relay was not actually receiving a false trigger signal, and then just re-wired it to only get power with key-on. Basically we no longer have the oil pressure protection but I just don't see this as a big concern. With gas, yeah, it'd be more worrisome.