HMMWV protective control box.
P/N 12446779 / WSU-4009UTA, NSN 6110013959585 EESS (Engine Electrical Start System) control box.
Do not mix EESS Prestolite/Nartron/KDS units with later model KDS Smart Start or Narton Smart Start temperature control units on same vehicle.
This control box must be used with temperature control unit part number 12338772.
Disconnect batteries before installing the control box. Failure to disconnect batteries before installing or removing control box connectors will damage the control box.
It is highly recommended to check the glow plugs before installing a new control box. Defective glow plugs may damage the control box.
The glow plug system will draw approximately 100 amps. The vehicle batteries must be in good condition for the preheat and start system to function. If the batteries cannot crank the engine they won’t operate the glow plugs.
Only the 60 amp alternators can power directly through the control box. Basic and A1 vehicles upgraded to 100, 200, and 400 amp alternators must have the alternator wiring harness modification in place (done when the alternator is installed) so the alternators output does not go through the control box. Vehicles factory equipped with 100, 200, and 400 amp alternators have the battery direct wiring factory installed.