DIN 72552 is a DIN standard for automobile electric terminal numbers, standardizing almost every contact in an automobile with a number code.
Ignition system
1 coil, distributor, low voltage
1a, 1b distributor with two separate circuits
2 breaker points magneto ignition
4 coil, distributor, high voltage
4a, 4b distributor with two separate circuits, high voltage
7 terminal on ballast resistor, to distributor
15 battery+ from ignition switch
15a from ballast resistor to coil and starter motor
Preheat (Diesel engines)
15 preheat in
17 start
19 preheat (glow)
Starter
50 starter control
Battery
15 battery+ through ignition switch
30 from battery+ direct
30a from 2nd battery and 12/24 V relay
31 return to battery- or direct to ground
31a return to battery- 12/24 V relay
31b return to battery- or ground through switch
31c return to battery- 12/24 V relay
Electric motors
32 return
33 main terminal (swap of 32 and 33 is possible)
33a limit
33b field
33f 2. slow rpm
33g 3. slow rpm
33h 4. slow rpm
33L rotation left
33R rotation right
Turn indicators
49 flasher unit in
49a flasher unit out, indicator switch in
49b out 2. flasher circuit
49c out 3. flasher circuit
C 1st flasher indicator light
C2 2nd flasher indicator light
C3 3rd flasher indicator light
L indicator lights left
R indicator lights right
L54 lights out, left
R54 lights out, right
AC generator
51 DC at rectifiers
51e as 51, with choke coil
59 AC out, rectifier in, light switch
59a charge, rotor out
64 generator control light
Generator, voltage regulator
61 charge indicator (charge control light)
B+ battery +
B- battery -
D+ dynamo +
D- dynamo -
DF dynamo field
DF1 dynamo field 1
DF2 dynamo field 2
U, V, W AC three phase terminals
Lights
54 brake lights
55 fog light
56 spot light
56a headlamp high beam and indicator light
56b low beam
56d signal flash
57 parking lights
57a parking lights
57L parking lights left
57R parking lights right
58 licence plate lights, instrument panel
58d panel light dimmer
Window wiper/washer
53 wiper motor + in
53a limit stop+
53b limit stop field
53c washer pump
53e stop field
53i wiper motor with permanent magnet, third brush for high speed
Acoustic warning
71 beeper in
71a beeper out, low
71b beeper out, high
72 hazard lights switch
85c hazard sound on
Switches
81 opener
81a 1 out
81b 2 out
82 lock in
82a 1st out
82b 2nd out
82z 1st in
82y 2nd in
83 multi position switch, in
83a out position 1
83b out position 2
Relay
85 relay coil -
86 relay coil +
Relay contacts
87 common contact
87a normally closed contact
87b normally open contact
88 common contact 2
88a normally closed contact 2
88b normally open contact 2
Additional
52 signal from trailer
54g magnetic valves for trailer brakes
75 radio, cigarette lighter
77 door valves control