Column: D1 char(100),
        D2 char(100),
        D3 char(100)

If the data are like the following:
(row 1) aaaaaa  bbbbb   cccc
(row 2) fffjfj  fdfdf   fjjj
(row 3) fjfjfj  jfjjf
(row 4) jjjjjj  jjjjj

load data
infile *
truncate
into table t1
FIELDS TERMINATED BY X'09' trailing nullcols
 (D1,
 D2,
 D3)
begindata
aaaaaa  bbbbb   cccc
fffjfj  fdfdf   fjjj
fjfjfj  jfjjf
jjjjjj  jjjjj

SQL> create table diagnosis (d1 varchar2(30), d2 varchar2(30), d3 varchar2(30));

Table created.

C:\Documents and Settings\Michel\Mes documents>sqlldr michel/michel log=d.log control=diagnosis.ctl

SQL*Loader: Release 10.2.0.3.0 - Production on Lun. Avr. 30 19:46:03 2007

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Commit point reached - logical record count 10

C:\Documents and Settings\Michel\Mes documents>type diagnosis.ctl
load data
infile 'diagnosis.csv'
into table diagnosis
fields terminated by "," optionally enclosed by '"'
(D1,
D2,
D3)

SQL> select * from diagnosis ;
D1                             D2                             D3
------------------------------ ------------------------------ ------------------------------
Cranial                        Congenital                     Anencephaly
Cranial                        Congenital                     Aqueductal stenosis
Cranial                        Congenital                     Ataxia telangiectasia
Cranial                        Congenital                     Cerebral palsy
Cranial                        Congenital                     Chiari I malformation
sdffffffffffffffff                                            fdssssssssssssss
fdssssssssss                   dfffffffffff                   dfddddddddd
sdffffffffffffffff                                            dff

8 rows selected.

Record 6: Rejected - Error on table DIAGNOSIS, column D3.
Column not found before end of logical record (use TRAILING NULLCOLS)
Record 7: Rejected - Error on table DIAGNOSIS, column D3.
Column not found before end of logical record (use TRAILING NULLCOLS)