Big Problem

[WSTSDE]

hey, i got a massive problem............

firstly my gps nav is not working, when i start the car the logo comes up the suddently wait wait it stays blank. I bought the car damaged it was hit from the rear, the gps box in the boot was damaged. So i bought 1 with the same no. on the back but last no. is diff so its correct. Plugged it in and nothing happens is ther a on button or soming also dont no is this help but also the front driver door speaker doesn't work aswell maybe from gps dont no....

Finally, the masssive problem the car doesn't rev trac is on doesn't turn off (ahhhhhh). When i got my car panel beated i had to remove the rear diff, fuel tank, etc. When i was putting it back ther was a box on top of the rear diff around 4 hoses coming from it one comes of the fuel tank and i did't no wre the other go could that box b the reason if so could sombody kindly check it out for me and tell me were they go.

or could it be because brake fluid is low.....

Its driving me insane.........PLEASE HELP........