Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

BRITISH STANDARD AUTOMOBILE SERIES

Specification for

Electrical connections
between 24 V trailer
antilock braking
systems and towing
vehicles

UD C [62 9. 1 1 - 592 ] . 01 3. 5: 62 1 . 31 6. 541

BS AU
196:1984


Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

BS AU 196:1984

Committees responsible for this
British Standard
The preparation of this British Standard was entrusted by the Automobile
Standards Committee (AUE/- ) to Technical Committee AUE/1 6 upon which the
following bodies were represented:
Association of Trailer Manufacturers
Department of Transport
Electric Cable Makers’ Confederation
National Caravan Council Limited

Society of Motor Manufacturers and Traders Limited

This British Standard, having
been prepared under the
direction of the Automobile
Standards Committee, was
published under the authority
of the Board of BSI and
comes into effect on

Amendments issued since publication

31 January 1 984
© BSI 02- 2000

The following BSI references
relate to the work on this
standard:
Committee reference AUE/1 6
Draft for comment 83/71 1 01 DC

ISBN 0 580 13544 6

Amd. No.

Date of issue

Comments



Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

BS AU 196:1984

Contents
Page
Committees responsible
Foreword

ii

1

Scope

1

2

Connectors

1

3

Antilock powering

1

4


Antilock failure warning

1

5

System identification

1

Figure 1 — Towing vehicle wiring (24 V)

2

Figure 2 — Trailer or semi- trailer wiring (24 V)

3

Publications referred to

© BSI 02- 2000

Inside front cover

Inside back cover

i



Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

BS AU 1 96: 1 984

Fore word

This British Standard has been prepared under the direction of the Automobile
Standards Committee. It is based on information sheet EE- 4R of the Society of
Motor Manufacturers and Traders, “SMMT recommended method for
powering 24 Volt trailer antilock braking systems”.
The connections between the towing vehicle and trailer are made through plugs
and sockets which are specified in BS AU 1 97 and BS AU 1 98.
It should be noted that it may be illegal to operate a vehicle on which the antilock
system is inoperative.
A British Standard does not purport to include all the necessary provisions of a
contract. Users of British Standards are responsible for their correct application.
C omp liance with a British S tand ard d oe s no t of itse lf confe r immunity
from le gal ob ligatio ns.

S ummary of p age s

This document comprises a front cover, an inside front cover, pages i and ii,
pages 1 to 4, an inside back cover and a back cover.
This standard has been updated (see copyright date) and may have had
amendments incorporated. This will be indicated in the amendment table on the
inside front cover.

ii

© BSI 02- 2000



Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

BS AU 1 96: 1 984

1 S cop e

4 Antilock failure warning

This British Standard specifies electrical

4.1

connections between towing vehicles and trailers or

fitted with a tell- tale that, when lit, indicates

Towing vehicles as described in

3.1

shall be

semi- trailers when 24 V antilock braking systems

defective functioning, defective condition or the

are fitted.


failure to function of the trailer antilock braking

NOTE

system.

The publications referred to in this standard are listed

on the inside back cover.

The tell- tale shall be 3 W maximum, red and located
in the forward field of vision of the driver and visible

2 C onne ctors

even by daylight.

Towing vehicles and trailers or semi- trailers shall
be equipped with a type 24 N (normal) connector
that complies with BS AU 1 97 and a type 24 S

function of the antilock braking system.
The tell- tale shall be 7 W maximum, green and

3 Antilock p owe ring

mounted so that it is within the field of vision of the

Towing vehicles shall be wired in accordance


driver’s mirror and visible even by daylight.

with Figure 1 when they are fitted with antilock

NOTE

braking systems or are intended to run with trailers
or semi- trailers equipped with antilock braking
systems.
The power supply via pin

j

The normal power of this tell- tale should be 5 W.

The circuits described in

4.1

and

4.2

shall also

warning tell- tale.
of the type 24 S

connector shall be switched by the main electrical


5 S yste m identification
5.1

The supply can be controlled by a relay, to relieve the

main electrical switch of the additional load, which can be an

Towing vehicles as described in

3.1

shall carry

a label that states that they are wired for trailer
antilock braking systems and equipped with an

intermittent maximum of 1 0 A.

Trailers or semi- trailers equipped with antilock

braking systems shall be wired in accordance
with Figure 2.
NOTE 1

4.3

include a check mode for the following failure

switch in the cab.


3.2

3.2,

functioning, defective condition or the failure to

BS AU 1 98.

NOTE

Trailers or semi- trailers as described in

tell- tale that, when lit, indicates defective

(supplementary) connector that complies with

3.1

4.2

shall be fitted with an antilock failure warning

electrical connector wired in accordance with
BS AU 1 96: 1 984
5.2

This allows for a secondary power source to protect

1)


.

Trailers or semi- trailers equipped with antilock

braking systems shall carry a label stating that they

antilock operation in the event of loss of the primary feed circuit.

are fitted with antilock braking systems that are

This secondary feed is provided by the stop lamp circuit which is

wired in accordance with BS AU 1 96: 1 984

connected to pin

j

NOTE 2
and

h

of the type 24 N connector.

When antilock braking systems are not fitted, pins

of the type 24 S connector need not be wired.

NOTE 3


f

5.3

1)

.

The label shall also describe the antilock failure

warning tell- tale check procedure.

It is recommended that the stop lamp circuit is not the

sole means of powering the antilock braking system.

1)

“Marking BS AU 1 96: 1 984 on or in relation to a product is a claim by the manufacturer that the product has been

manufactured to the requirements of the standard. The accuracy of such a claim is therefore solely the manufacturer’s
responsibility. Enquiries as to the availability of third party certification to support such claims should be addressed to the
Director, Quality Assurace Division, BSI, Maylands Avenue, Hemel Hempstead, Herts HP2 4SQ for certification marks
administered by BSI or to the appropriate authority for other certification marks. ”

© BSI 02- 2000

1



Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

NO TE

Figure 1 — Towing vehicle wiring (24 V)

C onnections as shown are to indicate princip le of operation only.

BS AU 1 96:1 984

2
© BSI 02 - 2 000


Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

BS AU 1 96:1 984

NO TE 1

The manufacturer of the antilock control unit should specify the blocking diode. The comp onent should b e part of the

control unit assembly.

f

and

j


NO TE 2

When antilock is not fitted p ins

NO TE 3

C onnections as shown are to indicate principle of operation only.

are not wired.

Figure 2 — Trailer or semi-trailer wiring (24 V)

© BSI 02 - 2 000

3


Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

4

blank


Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

BS AU 196:1984

Publications referred to

Specification for electrical connections between towing vehicles and trailers with 24 V electrical
equipment: type 24 N (normal).

BS AU 1 97,

BS AU 1 98, Specification for electrical connections between towing vehicles and trailers with 24 V electrical
equipment: type 24 S (supplementary).
Information sheet EE- 4R

2)

“SMMT recommended method for powering 24 Volt trailer antilock braking

systems. ” (Society of Motor Manufacturers and Traders. )

2)

Referred to in the foreword only.

© BSI 02- 2000


Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 01 : 57: 50 G M T+00: 00 2006, U n con trol l ed Copy, (c) BSI

BS AU
196:1984

BSI — British Standards Institution
BS I is the indep endent national b ody res p ons ib le for p rep aring
Britis h S tandards . It p res ents the UK view on s tandards in E urop e and at the

international level. It is incorp orated b y Royal C harter.

Revisions
Britis h S tandards are up dated b y amendment or revis ion. Us ers of
Britis h S tandards should make s ure that they p oss es s the latest amendments or
editions .

It is the constant aim of BS I to imp rove the quality of our p roducts and services .
We would b e grateful if anyone finding an inaccuracy or amb iguity while us ing
this Britis h S tandard would inform the S ecretary of the technical committee
res p ons ib le, the identity of which can b e found on the inside front cover.
Tel: 02 0 89 96 90 00. Fax: 02 0 89 96 7 40 0 .

BS I offers memb ers an individual up dating s ervice called PLUS which ens ures
that s ub s crib ers automatically receive the lates t editions of s tandards .

Buying standards
O rders for all BS I, international and foreign s tandards p ub lications s hould b e
addres s ed to C us tomer S ervices. Tel: 0 2 0 899 6 9 00 1 . Fax: 0 2 0 899 6 7001 .

In res p ons e to orders for international standards , it is BS I p olicy to sup p ly the
BS I imp lementation of thos e that have b een p ub lis hed as Britis h S tandards,
unless otherwis e requested.

Information on standards
BS I p rovides a wide range of information on national, E urop ean and
international standards through its Lib rary and its Technical H elp to E xp orters
S ervice. Various BS I electronic information s ervices are also availab le which give
details on all its p roducts and s ervices . C ontact the Information C entre.
Tel: 02 0 89 96 71 1 1 . Fax: 02 0 89 96 7 048.


S ub s crib ing memb ers of BS I are kep t up to date with s tandards develop ments
and receive sub s tantial discounts on the p urchase p rice of s tandards. For details
of thes e and other b enefits contact Memb ership Adminis tration.
Tel: 02 0 89 96 70 02 . Fax: 02 0 89 96 7 00 1 .

Copyright
C op yright s ub s is ts in all BS I p ub lications . BS I als o holds the cop yright, in the
UK, of the p ub lications of the international s tandardization b odies . E xcep t as
p ermitted under the C op yright, D es igns and Patents Act 1 988 no extract may b e
rep roduced, s tored in a retrieval s ystem or transmitted in any form or b y any
means – electronic, p hotocop ying, recording or otherwis e – without p rior written
p ermis s ion from BS I.

This does not p reclude the free us e, in the cours e of imp lementing the standard,
of necess ary details such as s ymb ols, and size, typ e or grade designations. If thes e
details are to b e used for any other p urp os e than imp lementation then the p rior
written p ermiss ion of BS I must b e ob tained.

If p ermis sion is granted, the terms may include royalty p ayments or a licensing
agreement. D etails and advice can b e ob tained from the C op yright Manager.
BS I
3 89 C his wick H igh Road
London
W4 4AL

Tel: 02 0 89 96 70 7 0.