How To Scan "improper dihedrals" in Gaussian 09?
After I asked this question, I found answer. I am putting the solution here so maybe somebody else use this. 
The solution is this: if gaussian exit from the job (for example) at step 6; change starting geometry and take it 6 step back. How? For example in my question every step size is 18 degree and step 6 is 90 degree. Open your *.gjf or *.com file select the same dihedral and decrease angle 90 by degree (don't forget 90 degree is just for this example, you wil change it according to your step and the size of step) *sometimes you may have to fix one group . And then start job again.

you can see my "wrong gjf file" in the question. And here is the my "right gjf file": I only changed the starting dihedral angles.

%nprocshared=4
# opt=modredundant am1 geom=connectivity

Title Card Required

0 1
 B                 -0.54526231    0.17208210    0.44752404
 H                  0.54967689    0.02475247    0.03303383
 H                 -1.22032311    1.04666245    0.03303383
 H                 -0.96514071   -0.55516861   -1.21043678

 1 2 1.0 3 1.0 4 1.0
 2
 3
 4

D 1 2 3 4 S 9 18.000000


NOTE: it seems I defined different dihedrals at first glance.
in question I defined:
D 4 2 3 1 S 10 18.000000 and here I defined:
D 1 2 3 4 S 9 18.000000 but out of the symmetry and all H bonds are equal two dihedrals are the same indeed. Here is the article about this:  https://pdfs.semanticscholar.org/ab92/5f43824e59dd9e3be3474ebbac57a64998c3.pdf (DOI 10.1002/jcc.21425  - "Symmetrization of the AMBER and CHARMM
Force Fields", 2009, EDYTA M. et all)
in this article in figure 5 shows only 3 different improper can exist for  I–J–K–L but in my question I=L=J and thus actually 1234 dihedral and 2314 dihedral are the same and gave the same results for the same technics.