340's up to 1983 were fitted with "conventional" distributor with points ignition, from the 1984 yr.model they were fitted with "mapped" electronic ignition made by Renix (a French company). The "Renix" unit is an ECU with a coil unit attached.
If your car has this the "coil" wiring is as follows.
In plug A terminal 1 provides a speed signal for the Rev Counter, the Tachometric relay (in CVT cars) and for the over-run fuel shut off system if fitted (1986 0n).
Terminal 2 is to ground (earth)
Terminal 3 provides a 12v+ supply from the ignition switch (via the fuse box (but not a fuse) and the ignition relay).
Plug B has two wires and connects to the flywheel sensor (on the bellhousing).
Plug C normally is not fitted on UK cars but terminal 8 gives a signal to the gear change indicator (1985 only I think).
However - one tip - If you run an 84,85,or 86 year car with a Type 402 Renix and suffer pinking on unleaded fuel you can retard the ignition timing by 4 degrees by earthing terminal 7.
The stored map differs from model to model and from year to year in some cases. The label on the ECU will give the code number that distinguishes the map. It is the 3 digit code in the second line of the label - not the larger 6 digit Renix part no.
B13.4E (1989 onwards) = 402 (was this ever available?)
B14.3E = 401 (not in UK)
B14.4E = 402 (from 1985 has change up indicator)
B14.4E = 412 (1987ish on) Retarded by 4 deg. to run on unleaded.
B14.4S (not UK) = 402
B172K (1985-1986)= 410
B172K (post 87) = 415
B19A = 404
B200E (1985-1986)= 405 or 408 (408 has engine speed limiter)
B200E (post 87) = 411
B200EA (Nordic market) = 441
B200F = 411
B200K (1985-1986) = 406 or 407 (from 1985 has change up indicator) (407 has speed limiter.)
B200K (post 87 ) = 414