If no power is supplied to M870A3 semitrailer ABS ECU or service lights
you may need to install an electrical system retrofit kit.
This article initially appeared in PS 720 (Nov 12), p. 61.
Some early production M870A3 semitrailers were built with an electrical system compatible with M916-series tractor trucks. But when hooked up to an M983A2 or M983A4 light equipment transporter HEMTT, no power is supplied to the semitrailer’s service lighting system and ABS electronic control unit.
Fix that by installing the electrical system retrofit kit, NSN 5995-01-598-1931. That keeps your semitrailer fully compatible with M916-series tractor trucks.