Outer Limits 4x4 Board

Just puting the wiring loom into the MK/Hummer, the Auto lecy is going to commodore wiring all hooked up for me, But there is a little black box next to the brake booster, see pic, it seems that I have miss placed it and was just wondering what it is??, the pic is of a replica hummer using the same commodore engine that I am using, so I must need it, just not sure what it is, any help would be great.
Oh the Mk K was originally a L28, not sure if the diesels had this box
Cheers
Hoppy

This replica Hummer was a diesel, so it seems they have it too..
Hoppy

Hint .....




Do ya windscreen wipers work ??????


Kingy

relay/control modules are ...... 12volt for L28 ..... 24volt for SD33

Cheers, they dont work cause the car is not wired up yet, i have just run the wiring loom through the firewall and I was just checking all the lables that I put on all the connections and realised that I dont have the black box, but now I know what it is, thanks Kingy
Hoppy.