Ok , here's a pdf on testing the LBCU ( Light Bar Control Unit ) the gauge package Freightliner started using in 2007 .
I haven't heard that they introduced a newer system so , hopefully this covers your year of chassis.
If not you'd be best to call Freightliners free help line with your chassis serial number , for any info they can provide on gauge testing .
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.