Thanks, Dave. That's very helpful. I'll check it out.
Originally Posted by pdxmotorhead
I believe the 990 has the "Low-Voltage-Disable" "Feature" by honking the horn you put a brief fairly high load on the battery, and that could improve the battery connection then improving the voltage reading to the ECU..
I'd check battery terminals, and voltage both at the battery terminals and the un-switched accessory fuse in the fuse box.. The difference should be minimal between them.