Low DEF Warning(?)... solved, at least partially

[MisterT]

Low DEF Warning(?)(Freightliner Dash readout)

...started on a Christmas trip for some time in sunny warm Florida, stopped in Charleston to see kin.

...left Charleston yesterday morning, with DEF dash indicator at 2 green bars, and two DEF containers in the bay to refill the tank when it drops to one bar.

BUT,

at about 25miles south, got a 'ding' sound and a 'Low DEF Warning' on the Freightliner Dash readout. There were still TWO green bars of DEF showing.
I kept going in order to get to a reasonable place to pull over and refill tank.
The DEF tank had a little RED light on, and slightly less than 1/4 tank. So, it looks like the dash readout and the tank readout are not in sinc. I refilled tank with two containers - DEF green bars are now full at FOUR.

BUT,

the Low DEF Warning did not go away. 10 miles later, another 'ding' and the 'CHECK ENGINE' light came on! Oh no, better pull over quick. I checked the Cummins manual, nothing. I went out and checked the DEF tank itself - still full, and no longer a RED indicator light on. (?) wow.

THEN,
I cut the engine off. Let it rest for a minute. Recranked, then 'voila'! the warning went away, as well as the 'CHECK ENGINE' indicator.

BUT,
now there was a new indicator, the MIL "Engine" outline - an indicator of something amiss with the Emissions(DEF I presumed). Ok, maybe it will go away in a little while...

A night later, and several times of cranking up the engine, and 'voila'! the new indicator light finally did not show again.... nice.


but confusing.... there is so little information, and so hard to track down, about these types of warning and indicator lights.
I guess I could have just called Freightliner, oh well.

SUMMARY:
if vacationing for Christmas, and your Low DEF Warning comes on, refill your DEF, watch for other lights and warnings, drive patiently to your destination, and wait for the warning lights to slowly fade away. It's all good.

[Stiltner]

Thanks for the info MisterT! I drop in 2.5 gallons when I hit 2 bars on the DEF indicator, and carry another 2.5 gallons in case I'm on the road. It's been my experience that most times when something like this happens, I shut down the coach, let it rest for a few, then restart and the electronics start working as they should.

[jones47172]

My Venetian did the same thing, low def light when not low. A call to Freightliner suggested I need to drive with several engine stop/starts cycles and all might be fixed. By the time I got to the next rest area and restarted the indication problem went away. Freighliner thinks they will have an updated LBCU for me in January when I go in for maintenance which will solve the issue. I have also had codes appear indicating lost communication with sensors (probably the DEF).

[Stiltner]

Don't hold your breath there Mike! I've had what Freightliner calls a LBCU problem on my new 2016 coach. My odometer resets to zero every time I hit the battery disconnect. I've been calling Freightliner every month since June 2016. The date always gets pushed by 30-60 days. Last report was that the engineering department is working with the vendor to resolve the problem. It works fine when bench testing but fails when installed into a coach. Recently I've been getting the loss communication sensor reading also. My problem may be compounded because I had electrical problems while under coach warranty and may not be able to tell if that issue was resolved until I got a reliable LCBU. Every time I turn the key, I also get Low Battery Voltage warning, even after being plugged into 50 amp shore power for 2-3 days. Freightliner has a list of RV owners for LBCU. You might want to get on the list.