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Subject:Re: What does terminal 15a do? (LVC)
From:Alistair Bell
Date:Fri, 18 Oct 2002 14:58:23 -0700

on 18/10/02 2:35 PM, Simon Reinhardt wrote:

> I'm using a wiring harness from an '88 GTI for my van's engine swap.
> There's a lead to the computer that is supposed to come from terminal
> "15a" on the starter, which of course the van doesn't have. Does anyone
> know what 15a is for?
> -Simon

Rushing to beat Unca Joel on this one (he posted this a few times before),
maybe it will help, a least its a good reference to have.

Alistair

From Bosch Automotive Handbook, 3rd edition

Terminal Designations  (Excerpts from DIN Standard 72 552)
The terminal designations do not identify the conductors, because device
with different terminal designations can be connected at the two ends of
each conductor.  If the number of terminal designations is not
sufficient (multiple-contact connections), the terminals are
consecutively numbered using numbers or letters whose representations
of specific functions are not standardized.  <<huh?>>

Terminal  Definition
-----------------------------------------------------------------------
          IGNITION
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
-----------------------------------------------------------------------
          GLOW PLUG AND STARTER SWITCH
17        Start
19        Preheat
-----------------------------------------------------------------------
          BATTERY
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
-----------------------------------------------------------------------
          ELECTRIC MOTORS
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
-----------------------------------------------------------------------
          STARTER
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
-----------------------------------------------------------------------
          TURN SIGNAL FLASHER
49        Input
49a       Output
49b       Output, second turn-signal circuit
49c       Output, third turn-signal circuit
-----------------------------------------------------------------------
          STARTER
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
-----------------------------------------------------------------------
          ALTERNATOR
51        DC voltage at rectifier
51e       DC voltage at rectifier with choke coil for daytime driving
-----------------------------------------------------------------------
          TRAILER SIGNALS
52        Signals from trailer to towing vehicle, general
-----------------------------------------------------------------------
          WIPER MOTOR
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)
-----------------------------------------------------------------------
          TRAILER SIGNAL
54        For lamp combinations and trailer plug connections
          TRAILER STOP LAMP
54g       Pneumatic valve for additional retarding brake,
          electromagnetically actuated
-----------------------------------------------------------------------
          LIGHTING
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
-----------------------------------------------------------------------
          TONE-SEQUENCE CONTROL DEVICE
71        Input
71a       Output to horns 1 & 2, low
71b       Output to horns 1 & 2, high
72        Alarm switch (rotating beacon)
-----------------------------------------------------------------------
          INTERIOR
75        Radio, cigarette lighter
76        Speaker
77        Door-valve control
-----------------------------------------------------------------------
          SWITCHES
----------(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
-----------------------------------------------------------------------
          CURRENT RELAY
84        Input, actuator and relay contact
84a       Output, actuator
84b       Output, relay contact
-----------------------------------------------------------------------
          SWITCHING RELAY
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
------------------------------------------------------------------------
          ALTERNATOR and VOLTAGE REGULATOR
          GENERATOR and GENERATOR REGULATOR
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
------------------------------------------------------------------------
Cross-reference for old and new terminal designations in accordance with
DIN 72 552.
Only terminal designations whose significance has altered are given.

OLD           NEW
1             1, 53(wiper), 53e
2             2, 53e
3             53, 53b(wiper)
4             4, 53a, 53b(wiper)
15            15, 49(turn-signal flasher)
15+           49
15/54         15, 49, 54
16            15a, 15
30            30, 33(motor)
30/51         30, 87, 88(relay)
30f           45
30h           45, 45a
30h I         45a
30h II        45b
30L           33L (motors)
30R           33R (motors)
31            31, 31c, 32(motors)
31a           31a, 31c
31B-          B-
50            50, 50b, 50f, 50h
50a           50, 50a, 50e, 50g
50b           50d
50k           50d
50 II         50c
51            51, 59, B+
51 -          59
51a           59
51B+          B+
54            54, 53a, 54g
54/15         15
54d           53(wiper)
54e           33b, 53b(wiper)
54L           49a
58            58, 58L, 58R
58b           58b, 58d
59            59a
85d           31b(alarm switch)
B+30          B+
B+51          B+
D+/61         D+
D-/61         D-
H             71
HL            L (L54b)
HR            R (R54b)
K             C
K0            C0
K1            C, C2
K2            C2
K3            C2, C3
K4            C2, C3
L54           L (L54)
N             55
P             C, 57a
PL            57L
PR            57R
R             R, 75
R54           R, (R54)
R54b          Rb
S             49a, 53(wiper)
S4            49a
SBL           (L54)
SBR           (R54)
VL            L
VR            R
+             15, 49(turn-signal flasher)
              53, 53a(wiper)
+2            53a
+15           49
-             1 (ignition coil), 31
------------------------------------------------------------------------
and, while i'm at it, here's some interesting stuff:

Power consumption of vehicle electrical leads (average values)

Backup lamps                       25W
Battery ignition                   20W
Blower motor                       80W
Cigarette lighter                 100W

Fog lights                         35W each
Fog warning lamp                   35W
    (red fog light on rear)
Glow plugs                        100W each
Headlamps, low beam                55W each

Headlamps, high beam               60W each
Heated rear window                120W
Horns and fanfare horns            25W...40W each
Instrument-panel lamps              2W each

Interior lamp                       5W
License-plate lamp                 10W
Parking lamp                        3W...5W
Radio                              10W...15W

Side-marker lamps                   4W each
Starting motor for truck          2.2kW...12kW
Starting motor for car            0.8kW...3kW
Stop lamps                         18W each

Tail lamps                          5W each
Turn-signal lamps                  21W each
Vehicle heater                     20W...60W
Windshield wiper                   90W