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Electrical Terminal Designations

September 23, 2010 | Troubleshooting & Repair

By Richard Millang

Ever wonder what those number codes are on the back of your 356 electrical devices?
Or the numbers shown on the 356 electrical diagram? Well, here it is. Please note this is a
comprehensive list that contains many codes in addition to 356 electrical items. May be useful
for some of us who also have BMW's, Volkswagens, Mercedes or 911's, etc.

Terminal Definition


1 Ignition coil, ignition distributor, low voltage

Ignition distributor with two separate electrical circuits

1a to ignition contact breaker I
1b to ignition contact breaker II
2 short-circuit terminal (magneto ignition)
4 Ignition coil, ignition distributor, high voltage

Ignition distributor with two separate electrical circuits

4a from ignition coil I, terminal 4
4b from ignition coil II, terminal 4
15 Switched + downstream of battery
(output of ignition/driving switch)
15a Output at dropping resistor to ignition coil and starter


17 Start
19 Preheat


30 input from + battery terminal, direct
30a input from + terminal of battery II
(12/24 V series-parallel battery switch)
31 Return line to battery - battery terminal or ground, direct
31b Return ine to negative battery terminal or ground, via switch or relay
(switched negative)

(12/24 V series-parallel battery)

31a Return line to - terminal of battery II
31c Return line to - terminal of battery I


32 Return line
(Polarity reversal possible at terminals 32-33)
33 Main terminal connection
(Polarity reversal possible at terminals 32-33)
33a Self-parking switch-off
33b Shunt field
33f For second lower-speed range
33g For third lower-speed range
33h For fourth lower-speed range
33L Counterclockwise rotation
33R Clockwise rotation


45 Separate starter relay output; starter input (main current)
45a Output, starter I
Input, starters I and II (Two-starter parallel operation)
45b Output, starter II (Two-starter parallel operation)
48 Terminal on starter and on start-repeating relay for monitoring starting procedure


49 Input
49a Output
49b Output, second turn-signal circuit
49c Output, third turn-signal circuit


50 Starter control (direct)
50a Output for starter control
(Series-parallel battery switch)
50b Starter control with parallel operation of two starters with sequential control
50c Input at starting relay for starter I
(Starting relay for sequential control of the engagement current during parallel operation of two starters)
50d Input at starting relay for starter I
(Starting relay for sequential control of the engagement current during parallel operation of two starters)
50e Input, Start-locking relay
50f Output, Start-locking relay
50g Input, Start-repeating relay
50h Output, Start-repeating relay


51 DC voltage at rectifier
51e DC voltage at rectifier with choke coil for daytime driving


52 Signals from trailer to towing vehicle, general


53 Wiper motor, input (+)
53a Wiper (+), self-parking switch-off
53b Wiper (shunt winding)
53c Electric windshield-washer pump
53e Wiper (brake winding)
53i Wiper motor with permanent magnet and third brush (for higher speed)


54 For lamp combinations and trailer plug connections


54g Pneumatic valve for additional retarding brake, electromagnetically actuated


55 Fog lamps
56 Headlamp
56a High beam, high-beam indicator lamp
56b Low beam
56d Headlamp-flasher contact
57 Side-marker lamp: motorcycles, mopeds. Abroad also cars, trucks, etc.
57a Parking lamp
57L Parking lamp, left
57R Parking lamp, right
58 Side-marker lamps, tail lamps, license-plate lamps and instrument-panel lamps
58b Tail-lamp changeover for single-axle tractors
58c Trailer plug-and-receptacle assembly for single-conductor tail-lamp cable with fuse in trailer
58d Variable-intensity instrument-panel lamp, tail-lamp and side-marker lamp
58L Side-marker lamp, left
58R Side-marker lamp, right; license-plate lamp

ALTERNATOR (magneto, generator)

59 AC voltage, output, rectifier, input
59a Charging armature, output
59b Tail-lamp armature, output
59c Stop-lamp armature, output
61 Alternator charge-indicator lamp


71 Input
71a Output to horns 1 & 2, low
71b Output to horns 1 & 2, high
72 Alarm switch (rotating beacon)


75 Radio, cigarette lighter
76 Speaker
77 Door-valve control/td>

Break-contact and changeover switches

81 Input
81a 1st output, break side
81b 2nd output, break side

Make-contact switches

82 Input
82a 1st output
82b 2nd output
82z 1st input
82y 2nd input

Multiple-position switches

83 Input
83a Output, position 1
83b Output, position 2
83L Output, left-hand position
83R Output, right-hand position


84 Input, actuator and relay contact
84a Output, actuator
84b Output, relay contact


85 Output, actuator (end of winding to ground or negative)
86 Start of winding
86a Start of winding or 1st winding
86b Winding tap or 2nd winding

Relay contact for break and changeover contacts

87 Input
87a 1st output (break side)
87b 2nd output
87c 3rd output
87z 1st input
87y 2nd input
87x 3rd input

Relay contact for make contact

88 Input

Relay contact for make and changeover contacts (make side)

88a 1st output
88b 2nd output
88c 3rd output

Relay contact for make contact

88z 1st input
88y 2nd input
88x 3rd input


B+ Battery positive
B- Battery negative
D+ Dynamo postive
D- Dynamo negative
DF Dynamo field
DF1 Dynamo field 1
DF2 Dynamo field 2

Alternator with separate rectifier

J Excitation winding positive
K Excitation winding negative
Mp Center point terminal
U,V,W Alternator terminals

DIRECTION INDICATOR (turn-signal flasher)

C First indicator lamp
C0 Main terminal connection for separate indicator circuits actuated by the turn-signal switch
C2 Second indicator lamp
C3 Third indicator lamp (e.g., when towing two trailers)
L Turn-signal lamps, left
R Turn-signal lamps, right