Autobrake disarm light ON but AACU bite shows nil faults : when you put autobrake selector to any position, autobrake disarm light is ON, but AACU bite shows nil faults. If this snag is hard on you can go for replacement of Autobrake selector panel located on P2-2 panel.
This panel contains a R1 relay which is not monitored by AACU.whenever the relay is latched in fault condition, autobrake disarm light comes on even without any system fault.
Thanks to Raghavendra for this input !
I had same defect on -800,found R1 rly contact
4-6 stuck in disarm pos.After rpl rly still no fix disarm lt keep coming
on.Found L A/T sw pack assy S-2 sw hi resist around 1kohm but after operate
throtle with meter hook up resist goes down to 1 ohm.Every time when resist
goes down able to engage AB.While doing bite msg was BOX A/B.