Discovery: Warning Buzzer / LBCU issues 08 Discovery 40X

[Bob Bowker]

Hi All
Thank you for this space..

Now for my issue..
I purchased a used 2008 - 40x knowing it had an issue with no gauges readings & air warning buzzer not shutting off at start up,
, BUT if I turned the headlight on, the problem would go away (until next start up)
After reading a bunch of threads here & talking to FL, I determined it was a daisy chain issue, so i thought..
FL had a TSB that had me replace all the white dash wires with the updated black ones
Well, the problem still exists, but got worse. Now the gauges will freak at random times and many miles of buzzer noise.
FL now says to replace the LBCU, but im not 100% confident they are correct.
They can not answer WHY turning on the headlights sometimes cures the problem.
Also, i read here of a way to test each gauge with the toggle, but FL didn't have any insight on that.

Any guidance would be appreciated
Thanks in advance

[RichKimball]

Sorry to hear of this common plight. I have abandoned attempting to get it all working correctly and have gone to a Fire tablet with a BlueFire dongle to provide all the needed info. In any case....to answer your question I have attached a LBCU Owners pdf to assist your needs. Best of luck.

[RichKimball]

Here is the wiring and pinout with data also.

[ktbt]

Pulling the two power fuses for the lbcu seems to do the trick, at least for me. I replaced the white wires with the black ones. It helped for a while, but the problem returned. I installed a dpst switch to interrupt power, thereby “rebooting” the lbcu. It’s working for now.

[Bob Bowker]

Originally Posted by RichKimball

Sorry to hear of this common plight. I have abandoned attempting to get it all working correctly and have gone to a Fire tablet with a BlueFire dongle to provide all the needed info. In any case....to answer your question I have attached a LBCU Owners pdf to assist your needs. Best of luck.

Thank you. There is great information in this pdf.

[Bob Bowker]

Originally Posted by ktbt

Pulling the two power fuses for the lbcu seems to do the trick, at least for me. I replaced the white wires with the black ones. It helped for a while, but the problem returned. I installed a dpst switch to interrupt power, thereby “rebooting” the lbcu. It’s working for now.

Where are these two fuses located ?

[ktbt]

In my expedition 38f they’re behind the center door under the dash between the seats. There should be a placard detailing the exact spot in the fuse box. I think the critical one is probably the constant hot fuse as opposed to the ignition hot fuse. At any rate, splicing the dpst switch removes all power to the lbcu forcing a reset to the unit. This seems to be a workaround for now.
That said, I still use the BlueFire app with my iPad mini.