Rolls-Royce Silver Shadow II - Testing the Electronic Automatic Speed Control System

0
;
Service
Bulletin
I ID> OLLS - l
Jf\\ OYCE I
I MOTORS I
Car Division
TSO 4171
Bl,1:e1:r. nurrber
SY/Ml04
(Issue 2}
Date
2
11 77
Pa ge
l of 6
Crc112.!;on 11st
II II I II
II II
II I I I I I
Category
C
ALL DISTRIBt"I'ORS AJ.~D RETAILERS
TESTI)TG THE ELECT~ONIC AUTO:t-'f.ATIC SPEED CONTP.OL SYSTE!1
J...PPLICABLE TO:
All Rolls-~oyce Silver Shadow II, Corniche and ca~argue Cars, and
all Bentley T2 and Corniche Cars.
I~TROCC'CTION:
T~e following is a test and fault diagnosis sequence to use on the
electronic speed control system to dete~ine problems.
In the near future a test box will be available to carry out
all checks.
Cl:".SCRI?':'.:'ION:
In the event of a speee control syste~ failure, fuse nurrher 9
should be checked. This fuse supplies power to the speed control
system and also to the direction incicators, brake lights, height
control solenoid and reversing lights. If the fuse is blown
and it continues to blow, then the above circuits must be checked to
establish the cause before proceedi ng further with the speedorr.eter.
P..ssuming that the replacement fuse d oes not blow, then t!1e soeed-control
sys~err. may be road tested for co r rec t operation. If it is still
inoperative or i £ the fu s e wa s intac t initially, then the
speedo~eter gene r ato r may also be ch ecked.
When the speedoreeter instrument is operating satisfactorilv, it
is unlikely that there is a fault in the generator sufficient to
cause a complete failure of the speed control. However, any
incorrect operation of the speecometer should be rectified and a
further road test given before proceeding with the speed control
fault diagnosis.