The message 
from Warwick Barnes  contains these words:

See bottom of message for WARNING

CORRECTED VERSION 3 Sept 03
Sorry had a slight orientation problem!

 Has anyone got any information on constructing the diagnostics I/O
 interface board and leads for use with "Testbook" software on a PC???


 there is a bit on my site, 
 www.users.zetnet.co.uk/barnes_firsnorton


 Also
 www.planetfall.com/~jeff/obdii
 www.andywhittaker.com
 www.opendiag.org
 freediag at sourceforge

 I have hopefully  identified the pins on the 14cux and have narrowed
 diagnostics down to

 pin 9 white/light green
 pin 18 white/pink
 pin 31 black/green looped back to earth when connector not attached to
  external diagnostic plug but attached to keeper plug in vehicle.

 on this basis I am suspecting that pins 9 and 18 are the ISO9141 K & L
 lines but which is which?
 
  FROM LATER
  A suggestion from NG article on burgular alarms suggests that 
    the K line is pink
  
 the diagnostic sockets are 5 pin shake proof and the lucas tester
 diagnostic lead is terminated as follows with an additional connector to
 connect to vehicle cigar lighter or battery.

  x O
 O x O

 where O shows a connection ; and x no wire attached. looking at end

 the air suspension diagnostic adapter plug is:-
 NB female pins come in a male shroud and vice versa
 
 female    male   pins
  x O      O x      treating this as  1 2
 O O O    O x O                      3 4 5
 male    female  shroud

 then 2 pin female connects to 1 male i.e. straight through
 then 3 pin female connects to 5 male i.e. straight through
 then 5 pin female connects to 3 male i.e. straight through
 then 4 pin female connects to 5 female

 this suggests 

  O x
 O x O

 in the vehicle with
 pin 1 K or L
 pin 3 loopback
 pin 5 K or L

 can anybody confirm this and add any useful information, particularly as
 to which is L and which is K

 One source who got a look inside says that ECM pins 9 and 18 run
 straight to the motorola microprocessor chip's serial ports, and as near
 as I can determine from Motorola docs these ports are bi-directional so
 should serve for ISO9141 K & L lines.
 note they are set to input after a reset!

Now had a chance to examine vehicle 1993 efi 3.9 with lucas 14cux for
both efi and air suspension. the wabco is a completely different plug; I
am not even going there till I get some solid information.

Air suspension

male pins "O" looking at end. This is end connected to ecu

 O x       using  1 2
O O O            3 4 5

(this matches adapter cable tester side pins exactly)
pin 1 white/green stripe wire 
    2 not connected
    3 black
    4 black/pink stripe
    5 white/pink stripe

female pins "O" loopback/keeper looking at end

 x x
x O x

pin 4 black wire
pins 1 2 3 5 not connected

Electronic fuel injection

male pins looking at end. This is end connecting ecu to diagnostic cable.

 O x    using 1 2
O x O        3 4 5

pin 1 white/green (**? ecu pin 9 )
    2 not used
    3 black       (**? earth)
    4 not used
    5 white/pink (**? ecu pin 18 )

female pins loopback connector/keeper looking at end

 x x
O x O

pin 3 is connected to pin 5 which then runs out a black/green wire
(**?ecu pin 31)

NB the range rover manual does not show a connection between 3 and 5
whilst the ETM shows a connection but on the diagnostic half not the
loopback half
it would seem that in normal operation both ECU pins 18 and 31 are set
to ground.
I just discovered the correct reference for pins is as follows:-
female pins     male pins
5 3 1            1 3 5
 4 2              2 4
looking at the ends; they match up when put together, Honest! :-)

The only other piece of information I have gleaned from the ISO/SAE
specs is that the L line input resistance to ground is not less than 5
Kohm even if ecu not in operation, and apart from initialisation it
should idle in logic state 1 (about 8 1/2 to 12 volts). This would
suggest that the L line should not ever be tied to ground, making it pin
9 on the ecu and my pin 1 (officially 4 ) on the diagnostic socket.

2004 Rovercom man says if you get K & L muddled up it won't blow the 
ECU : I really hope he is correct.

THERE IT IS: best guess K line pin 18
                        L line pin  9
                        

WARNING if you use this information you do so at your own risk, we cannot vouch for it's correctness, and do not accept any liability for bad things happening if you use this data.

If you have better information we would be pleased to have a copy Thank You.

Chris Barnes